



/\ • 













'^ *.,■•• .(j,^ 



5°^ 





.S^n 








5°^ 
















,^0*v 



^ » o « o - .0 -^ 'fit 








<^ * 6 « - .V 




.-i^^ 



^'\!^a^*. ^^^ .^"^ ^'* 










"^o^ 










■?^ 























V^ ,^L'^ 



'^^ ..^ »'^l^'". ^^ c'T /^* 



^..♦^ o^ 
















-"^o 










«5'^"-. 










• ■8.* -^ • 












.^ ... 




J.^ 










0* \.''.-- v-^ %'^^-0** V--f.^-'A* %'^^-.0«* \.''f.^.'A* *^^-?? 






V M O 















x^-y V^^V x^^V V»V V^^V" v^^-, 

'.-^flj."- y^jR^-X .'•".-^k."- ./%^^'\ c^.j^i.^ >\c,:^/^ 
















Bureau of Mines Information Clrcular/1 988 



Tin Occurrences Near Rocky 
Mountain (Lime Peai(), East- 
Central Alasica 

By J. Dean Warner, D. C. Dahlin, and L. L. Brown 




UNITED STATES DEPARTMENT OF THE INTERIOR 




Information Circular 9180 



Tin Occurrences Near Rocky 
Mountain (Lime Peak), East- 
Central Alaska 



By J. Dean Warner, D. C. Dahlin, and L. L. Brown 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Donald Paul Model, Secretary 

BUREAU OF MINES 

David S. Brown, Acting Director 




(\ 



h 






Library of Congress Cataloging-in-Publication Data 



Warner, J. Dean. 

Tin occurrences near Rocky Mountain (Lime Peak), east-central Alaska. 

(Information circular/Bureau of mines ; 9180) 
Bibliography: p. 13-14 
Supt. of Docs, no.: I 28.27 

1. Tin ores -Alaska -Lime Peak. I. Dahlin, D.C. (David Clifford), 1951- II. Brown, 

L.L. (Lawrence L.), 1928- III. Title. IV. Series: Information circular (United States. 

Bureau of Mines) ; 9180 

TN295.U4 [QE390.2.T48] 622 s [553.4'53'097986] 87-600146 



CONTENTS 



Page 

Abstract 1 Surficial geology of the North Fork Preacher 

Introduction 2 Creek 9 

Acknowledgments 2 Sampling and analyses 11 

Location and land status 2 Placer tin resources 12 

Physiography 3 Summary and conclusions 13 

Previous work 3 References 13 

Regional geology 3 Appendix A. -Description of igneous rocks mapped 

Lode investigations 3 near Lime Peak 15 

Geology of the Lime Peak pluton 3 Appendix B.- Description of greisen occurrences 

Lode (greisen) occurrences 4 sampled near Lime Peak 17 

Geochemical sampling and analyses 7 Appendix C. - Results of analyses of rock samples col- 
Bulk sampling and analyses 8 lected from the Lime Peak area 19 

Beneficiation 8 Appendix D. - Results of analyses and calculated tin 

Lode tin resources 9 grades of placer samples collected along North 

Placer investigations 9 Preacher Creek 24 



ILLUSTRATIONS 



1. Location map 2 

2. Tectonostratigraphic map of the Yukon-Tanana physiographic province with inset map showing the Lime Peak 

pluton and the North Fork of Preacher Creek 4 

3. Geologic and sample location map of Lime Peak area 5 

4. Geologic and sample location map of Bedrock Creek area 6 

5. View looking southeast showing main branch and east and west forks of Bedrock Creek 7 

6. Paragenesis of alteration and mineralization at Lime Peak 7 

7. SEM micrograph and X-ray element map showing cassiterite in a chlorite matrix 8 

8. Photograph looking northeast (downstream) along the headwaters of the North Fork of Preacher Creek from a 

position near the center of section 10 10 

9. Surficial geologic and sample location map for the North Fork of Preacher Creek 10 

10. Flow diagram depicting laboratory sample reduction and examination method 11 

11. Variation of tin grade along the North Fork of Preacher Creek 12 

B-1. Results of fluid inclusion analyses 17 

B-2. SEM micrograph of crystals of columbium-bearing rutile in a chlorite and quartz matrix 18 



TABLES 

1. Head analyses of bulk samples of greisen collected at Lime Peak 8 

2. Metallurgical balance for tabling composite bulk sample 9 

3. Metallurgical balance for tabling and flotation of sample 99 9 

4. Swell factors calculated from gravel samples 11 

5. Placer sample concentrate mineralogy and relative amounts of minerals 12 

6. Analysis and relative tin concentrations of panned concentrate samples 13 

A-1. Composition of Lime Peak pluton samples 15 

C-1. Results of quantitative geochemical analyses of rock samples 19 

C-2. Results of semiquantitative emission spectrographic analyses of rock samples 22 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 


°C degree Celsius 


mg 


milligram 


cm centimeter 


mg/pan 


milligram per pan 


cm^ cubic centimeter 


mi^ 


square mile 


ft foot 


MMlb 


million pounds 


ft^ square foot 


MMst 


million short tons 


ft^ cubic foot 


m.y. 


million years 


g gram 


mm 


millimeter 


gal gallon 


^m 


micrometer 


in inch 


pet 


percent 


lb pound 


ppm 


part per million 


Ib/st pound per short ton 


wt pet 


weight percent 


Ib/yd^ pound per cubic yard 


yd3 


cubic yard 



TIN OCCURRENCES NEAR ROCKY MOUNTAIN (LIME PEAK), 

EAST-CENTRAL ALASKA 



By J. Dean Warner/ D. C. Dahlin,^ and L. L Brown^ 



ABSTRACT 



In 1984 and 1985, as part of its critical and strategic minerals studies, the Bureau of 
Mines investigated lode and placer tin occurrences near Rocky Mountain (Lime Peak), in 
east-central Alaska. The lode occurrences consist of mineralogically complex, generally 
fault-controlled veins, and contain an average of approximately 0.05 pet Sn, as 
cassiterite. Beneficiation testing of two bulk samples of the vein material produced con- 
centrates containing 65 and 59 pet of the total tin values at grades of 0.35 and 13.9 pet, 
respectively. Although as much as 30 million short tons (MMst) of mineralized rock con- 
taining up to 20 MMlb Sn may be present, the grade of these occurrences is too low to be 
considered economic at this time. 

Trace amounts of cassiterite were also identified in surface samples of glacial out- 
wash gravels collected along North Fork Preacher Creek, which partially drains the area 
of tin lode deposits near Lime Peak. Low tin grades in the samples do not account for the 
former erosion of a large volume of lode tin mineralization from near Lime Peak; higher 
tin grades may be present in gravels closer to bedrock. 



^ Geologist, Alaska Field Operations Center, Bureau of Mines, Fairbanks, AK. 
2 Metallurgist, Bureau of Mines, Albany Research Center, Albany, OR. 
' Geologist, Albany Research Center. 



.•WTW^HBP 



INTRODUCTION 



The Bureau of Mines has intermittently investigated 
lode occurrences of tin and other metals in the Lime Peak 
(Rocky Mountain*) area since 1977. These investigations 
have been conducted as part of the Bureau's Alaskan critical 
and strategic minerals study, the goal of which is to identify 
reserves or resources of certain critical and strategic 
minerals that could be developed in times of prolonged na- 
tional shortage. The investigations have also been partially 
motivated by the Federal Bureau of Land Management's 
need for mineral data in the Steese and White Mountains 
National Conservation and Recreation areas. 

Results of Bureau reconnaissance investigations in the 
Lime Peak area prior to 1984 are presented in Bureau ol 



Mines Open File Report 31-85 (1).^ That report identifies an 
area of tin lode mineralization on the southeastern flank of 
the Lime Peak summit warranting further study and recom- 
mends that North Fork Preacher Creek be investigated for 
placer tin. 

This report presents results of detailed investigations of 
the lode and placer tin occurrences identified in reference 1. 
Numerous occurrences of sub-ore-grade lode tin mineraliza- 
tion as well as low-grade concentrations of placer tin were 
located. Although the lode occurrences contain relatively 
large tonnages of resources, the tin grades are too low to be 
considered economic at this time. 



ACKNOWLEDGMENTS 



This report has benefited from geologic and 
geochemical data donated to the Bureau by Mapco Minerals. 
Florence Weber, geologist, U.S. Geological Survey, assisted 
field investigations in 1977 and 1985 and provided the inter- 



pretation of glacial geology present in this report. David 
Menzie, geologist, U.S. Geological Survey, provided 
logistical assistance to a portion of the fieldwork in 1984. 



LOCATION AND LAND STATUS 



Lime Peak is located in the Circle (C-6) quadrangle, 
Alaska, approximately 58 miles northeast of Fairbanks, in 
the White Mountains (fig. 1). The study area straddles the 
boundary between the White Mountains National Recrea- 
tion Area to the west and the Steese National Conservation 

■* Although Rocky Mountain is the newly assigned name, the name Lime 
Peak is retained in this report because it is more widely known. 



Area to the east. Both areas are administered by the 
Federal Bureau of Land Management, as authorized in 1980 
by the Alaska National Interest Lands Conservation Act 
(Public Law 96-487), and are currently (1987) closed to 
mineral entry. 

■' Italic numbers in parentheses refer to items in the list of references 
preceding the appendixes at the end of this report. 



148" 

_J 



146" 

I 



Sleeit Notional 
Coniervotion Arao 
(northern portion) /^ 




-' 



Figure 1.— Location map. 



PHYSIOGRAPHY 



The White Mountains comprise the northwestern por- 
tion of the Yukon-Tanana physiographic division (2). Over 
much of its area, this province is characterized by a deeply 
eroded terrain of moderate relief with tundra- or mixed 
spruce- and birch-covered, gently rounded slopes and 
relatively flat ridgelines. Near Lime Peak, however, and 
elsewhere in areas with elevations above approximately 



2,500 ft, steep rubble-covered unvegetated hillsides are 
characteristic. In areas of higher elevation that are 
underlain by granitic rocks, rock spires (tors) are common. 
Most of the Yukon-Tanana region has escaped the effects of 
continental glaciation; however, broad U-shaped valleys in 
many of the more elevated areas of the White Mountains fit- 
test to former valley glaciation. 



PREVIOUS WORK 



Intrusive rock was initially mapped in the Lime Peak 
area by Prindle (3), in 1913. Most recently, in 1983, the area 
was geologically mapped by Foster {4.). In 1981, Wilson ob- 
tained a potassium-argon age of 56.7 ± 0.95 m.y. on biotite 
from the Lime Peak pluton (5). 

The Lime Peak pluton was first publicly recognized as 
tin bearing by Barker, in 1978, who found anomalously high 
concentrations of tin, columbium, lead, tungsten, zinc, 
uranium, and yttrium in heavy mineral concentrates panned 
from streams draining the pluton (6). Subsequent investiga- 
tions summarized by Burton in 1984, identified two major 
geochemically anomalous drainage areas near the Lime 
Peak pluton and numerous occurrences of tin-bearing veins 



(1). Burton recommended a more detailed investigation of 
mineralized zones in the Lime Peak summit area and poten- 
tial placer tin occurrences in the North Fork Preacher 
Creek area. In 1983, Menzie identified the Lime Peak area 
as permissive to the occurrence of tin deposits (7). 

Several mineral exploration companies have in- 
vestigated the Lime Peak area for deposits of tin, uranium, 
tungsten, and other metals. Most notably, following an air- 
borne radiometric survey in 1978, Mapco Minerals Co. 
located a large claim block just south of the Lime Peak sum- 
mit. Mapco drilled one shallow diamond drill hole, but ap- 
parently did not encounter significant mineralization. 



REGIONAL GEOLOGY 



The Lime Peak pluton is one of five early Tertiary- 
and/or Late Cretaceous-age plutons exposed in the White 
Mountains (4). The composition of these intrusions is similar 
to that of known tin-bearing intrusions elsewhere in the 
world; tin mineralization similar to that associated with the 
Lime Peak pluton has been identified in one other pluton in 
the White Mountain area. The intrusions are composite 
biotite granites; however, minor to major amounts of 
muscovite, hornblende, and tourmaline are locally present 
and rock compositions include quartz monzonite {1, 4, 8). 

These plutons intrude a diverse assemblage of variably 
metamorphosed and deformed upper Precambrian- to mid- 
dle Paleozoic-age sedimentary and mafic volcanic rocks that 



have been partially imbricated along northeast-trending 
thrust faults (fig. 2). Northwest of Lime Peak, the rocks 
consist of sequences of early Paleozonic shales and cherts 
and middle Paleozoic mafic volcanic and clastic and 
calcareous sedimentary rocks that comprise the Livengood, 
White Mountains, and Kandik River tectonostratigraphic 
terranes of Churkin {9). Southeast of Lime Peak, on the 
other hand, the rocks consists of variably metamorphosed 
lower Paleozoic-age quartzites and shales and comprise the 
Beaver and Yukon Crystalline terranes. The boundary be- 
tween the latter two terranes has been variably interpreted 
as gradational or thrust faulted {10). 



LODE INVESTIGATIONS 



In 1984, an 8-mi2 area located near the southeastern 
flank of the Lime Peak summit, and outlined on figure 2, 
was mapped and sampled in detail (figs. 3-4). The area con- 
tains numerous occurrences on tin lode mineralization and is 
centered around an east-flowing stream that forks near its 
headwaters. This stream and its forks are referred to as 
Bedrock Creek and the east fork and west fork of Bedrock 
Creek, respectively, in this report (fig. 5). 



GEOLOGY OF THE LIME PEAK PLUTON 

Because intrusions associated with tin mineralization 
worldwide are known to display specific geologic attributes 
(for instance, see Taylor {11) or Hudson {12)), considerable 
effort was made to document the geology of the Lime Peak 



pluton. The following paragraphs briefly summarize the 
results of geologic mapping near Lime Peak (fig. 3); more 
detailed descriptions of the pluton and its various phases are 
presented in appendix A. In general, the geology of the 
Lime Peak pluton is comparable to that of many tin- 
mineralized plutons worldwide. 

The Lime Peak pluton is a composite intrusion that out- 
crops over approzimately 30 mi^ and is elongate to the 
northeast, parallel to the regional structural grain (fig. 2). 
The intrusion is exposed over 2,500 vertical ft with abun- 
dant rubble above 3,500-ft elevation and exhibits a sharp 
and steeply southeast-dipping and northeast-trending con- 
tact with metasedimentary rocks to the southeast (i). The 
lack of roof pendants or other country rock xenoliths, the 
relatively coarse-grained nature of most of the intrusive 
rocks, and the steep intrusive rock-country rock contacts 




K 

"w" 

L 



YT 



While Mountain lerrane. Ordlvlcean mafic 
volcanic rocks grading Into Silurian and 
Devonian I Imeatone 

Llvengood terrene, early Paleozoic allele and 
cherts overlain by Devonlen claatlc rocks 

Beaver terrene, Cambrian quartzlte and shale 



Yukon Crystalline terrene, Paleozolc(7) 
and/or Precambrlan composite melemorphic 
terrene composed mostly ol sedlmentery 
rocks with continental origins 

Alluvium 



Contact 

High-angle fault, dashed where approximate 

Thrust fault, dashed where presence uncertain 



Lime Peak pluton 



on 


>:/ 


her C^iti ■" 

r : 




J 


y 


See figure 9 



■■\ 






•k 



■ ■ .\ 



\:?) 



20 40 

_J I 



Scale, miles 



Figure 2.— Tectonostratigraphic map of the Yui<on-Tanana physiographic province with inset map showing the Lime Peal< 
pluton and the North Fork of Preacher Creek. 



suggest the Lime Peak pluton is a deeply eroded mesozonal 
pluton. 

Two major intrusive phases were mapped m outcrop 
and rubble in the study area (fig. 3). These two phases, 
coarse-grained granite (Tgc) and finer granied porphyritic 
granite (Tgp), form most of the Lime Peak composite 
pluton. Several rhyolite, andesite, and lamprophyre dikes, 
however, were also mapped near Lime Peak (figs. 3-4). 

The contact relationship and relative ages of the coarse- 
grained and porphyritic granties are uncertain because of 
the extensive rubble cover. Where approximately located in 
the field, however, the contact between the two rock types 
appears to be relatively sharp, with rubble of one type 
grading into that of the other over a distrance of a few tens 
of feet. Although no crosscutting relationships were ob- 
served, the more lithophile-element-enriched nature of the 
porphyritic granite (see appendix A) suggests that it is the 
younger phase. 

Numerous faults cut the Lime Peak pluton. Where ex- 
posed, the faults invariably trend northwest and are steeply 
dipping; however, a few outcrops of shallowly dipping faults 
were also observed. The most laterally extensive fault 
parallels Bedrock Creek, extending 9,000 ft west-northwest 
from at least the southeastern intrusive contact. Slicken- 
sided rubble on strike near sample site 55 (fig. 3) suggests 
this fault may extend to the northern flank of the Lime Peak 
summit and beyond. 



LODE (GREISEN) OCCURRENCES 

Greisen is a term referring to a hydro thermally altered, 
generally granitic rock composed mostly of variable 
amounts of quartz, mica, chlorite, topaz, fluorite, or tour- 



maline, as well as other alteration minerals, and the ore 
minerals cassiterite, scheelite, wolframite, molvbdenite, and 
bismuth {11, 13). 

Near Lime Peak, greisen is abundant in rubble and 
locally present in outcrop (figs. 3-4). The greisen generally 
comprises from less than an inch to several-foot-wide 
veinlike altered zones and faults that trend northwest or 
west-northwest. The lack of outcrops makes determination 
of mineralized widths difficult; however, the size of rubble 
boulders, together with the width of the few occurrences 
that could be channel sampled, suggests the veins are 
mineralized over an average width of 2.0 ft. 

In outcrop, these veins are rarely traceable for more 
than a few tens of feet. Discontinuously exposed greisen and 
linear accumulations of greisen rubble, however, suggest 
that some greisen veins may extend for several thousand 
feet along strike and comprise several closely spaced occur- 
rences over widths of up to 100 ft (fig. 3). 

To the unaided eye, the greisen appears to consist of 
mostly manganese- and iron-stained quartz- and chlorite- 
altered granite with disseminated fluorite and pyrite and 
local crosscutting veinlets containing various mixtures of 
quartz, topaz, fluorite, tourmaline, pyrite, and chalcopyrite. 
Microscopically, however, the greisen is seen to consist of 
more complex alteration and mineralization assemblages. A 
paragenetic diagram listing the identified minerals and sum- 
marizing their crosscutting relationships is given in figure 6 
and a detailed description of the greisen is given in appendix 
B. 

In general, two alteration-mineralization assemblages 
are represented. Tin mineralization generally is restricted 
to the younger (stage 2) assemblage. Tungsten mineraliza- 
tion, on the other hand, is generally associated with the 
older (stage 1) assemblage. Cassiterite was observed by 



! i 



I |. I 1 Is 



> 5 y j ""4 \ <D o o 




CO 
O 

Q. 

« 

E 



o 

Q. 

m 

E 
c 
.2 

CO 

o 
_o 

a 
E 

(Q 
M 



(0 
U 

'5) 

o 
o 

(D 

O 

I. 

pi 

0) 















h 



3 o Si o » o -i 



\ 'k 



— -* < 






/ 



® *-\ — 
_ ' ' ' S 






'>/- 
./\*-l 









^'^= 







Q. 
(0 

E 
c 
.2 

w 
u 
o 

o. 
E 

(0 
(A 

■o 
c 



o 

o 
» 
o 

I 

0) 

3 



r- J^<D 

- r\\ (D 







Figure 5.— View looking southeast showing main branch 
and east and west forks of Bedrock Creek. 

scanning electron microscope (SEM) in sample 98, where it 
occurred as a few scattered grains ranging from 10 to 100 
/tm in size (fig. 7). Despite a careful search, no other tin- 
bearing minerals were identified in this or other samples of 
greisen. 

GEOCHEMICAL SAMPLING AND ANALYSES 

One hundred seventy samples of minerahzed rock were 
collected for geochemical analyses from the Lime Peak area 
during this investigation. Many of these are grab samples of 



rubble that consist of random chips collected within a few 
feet of the sample station. Some grab samples, however, 
were collected over larger, measured areas or along 
measured lengths in order to better evaluate the average 
grade of the mineralized rock in that area. Outcrops were 
sampled either by channeling a uniform volume of rock over 
a measured width or by collecting random or continuous 
chips from the portion of outcrop of interest. 

Samples were crushed, split, and pulverized by a com- 
mercial laboratory. Subsequently, most were analyzed by 
the Bureau of Mines Reno (NV) Research Center for tin, 
tantalum, and columbium by X-ray fluorescence (XRF), for 
tungsten by colorimetry, for thorium by radiometric tech- 
niques, for uranium by fluorimetric techniques, and for gold 
and silver by fire assay-inductively coupled plasma tech- 
niques. Each sample was also analyzed for a suite of 40 
elements by emission spectrometry. Splits of samples con- 
taining less than 50 ppm Sn were also analyzed by atomic 
absorption. Sample locations are shown on figures 3 and 4, 
and results of trace element analyses are given in appendix 
C. 

Samples of greisen collected in the Lime Peak area con- 
tain up to 7,100 ppm Sn as well as locally anomalously high 
concentrations of arsenic, beryllium, boron, columbium, 
copper, gold, iron, lead, lithium, manganese, silver, stron- 
tium, tungsten, uranium, and zinc (table C-1 and C-2). Most 
samples with tin concentrations greater than 600 ppm were 
collected either from the northwest-trending ridge north of 
Bedrock Creek or from isolated occurrences of greisenized 
faults exposed in the Bedrock Creek area (figs. 3-4). Many of 



Zircon* (rare 
uranlnlte inclusions) 
Monazlte* 
Xenotlme* 
Thorite' 
Quartz 
Alblte 

IMolybdenlte 
Cb-W-Fe mineral) 

(wolframoixlollte?) 
Fe-rich muscovlte) 
Topaz 
Fluorlte 
Sericite 
Tourmaline 
Casslterite 
Chalcopyrite 
Pyrlte * 
Bismuth minerals 

(bismuthlnlte, native Bi) 
Calclte 
Sphalerite 
Galena 

Ce>Y mixed oxide minerals 
Chlorite 

Cb-bearing rutile 
Kaollnite 
Fe oxides 
Mn oxides 
Pb oxides 

(cerrusite?) 
Malachite and chrysocolia 
Ca-Fe-U Mineral 



Older. 



.Stage 1. 



.Stage 2. 



Younger 



'These minerals are common inclusions in chlorite and iron-rich muscovite, but iikeiy represent residual minerals that originated as inclusions 
In blotlte. 

Figure 6.— Paragenesis of alteration and mineralization at Lime Peak. Vertical line represents time at which faulting was initiated. 
Solid line represents ubiquitous minerals; broken line represents occasional or Inferred presence. 



Table 1.— Head analyses of bulk samples of greisen collected 
at Lime Peak, percent 



Sample 


Cu 


F 


Fe 


Pb 


S 


Sn 


W 


Zn 


32 


. 0.02 


0.42 


19.2 


0.13 


0.02 


0.04 


<0.01 


0.21 


89 


. .04 


.59 


6.9 


.06 


.02 


<.02 


<.01 


.07 


98 


. .01 


.27 


16.7 


.04 


.57 


.03 


<.01 


.10 


99 


. .07 


.63 


20.9 


.38 


3.95 


.18 


<.01 


.26 




Figure 7.— SEM micrograpli {A) and tin X-ray element map 
(B) showing cassiterite (white) in a chlorite (gray) matrix. 

the samples in the ridge area also contain elevated concen- 
trations of arsenic, copper, lead, silver, or zinc; however, 
there is no apparent correlation between concentrations of 
tin and other metals. 

In contrast, elevated concentrations of beryllium, col- 
umbium, gold, and tungsten are generally confined to 
greisen sampled in the upper forks of Bedrock Creek. Most 
of the higher concentrations of beryllium and tungsten were 
found in samples containing the paragenetically older (stage 
1) mineral assemblages; higher concentrations of tin were 
found in samples containing the younger (stage 2) 
assemblages. 

The average tin content of samples of stage 2 greisen is 
475 ppm. The weighted average of all channel or continuous 
chip samples of stage 2 greisen is also 475 ppm Sn over an 
average width of approximately 2 ft. The average tin con- 
centration of samples collected on the northwest-trending 
ridge north of Bedrock Creek is 735 ppm. 



BULK SAMPLING AND ANALYSES 

Four bulk samples of greisen, each weighing 100 to 200 
lb, were collected at Lime Peak for mineralogical and 
metallurgical characterization. Sample locations are shown 
on figures 3 and 4 and head analyses are summarized in 



table 1. Sample 32 is from a 4.5-ft-long channel across two 
stage 2 greisen veins, 1.7 and 0.7 ft wide. These two veins 
are part of an up to 100-ft-wide zone of greisen veins that 
can be traced for 6,000 ft along strike. Sample 89 is a grab 
sample from a 12- to 15-ft-wide rubble train of massive 
stage 2 greisen that can be traced for 100 ft and inferred for 
1,000 ft along the strike. Sample 98 is from a 3-ft-wide chan- 
nel across a stage 2 greisen vein that consists of quartz- 
chlorite and massive chlorite greisen with traces of pyrite 
and fluorite. Sample 99 is from a channel across a 1.0-ft- 
wide stage 2 greisen vein consisting of a 0.6-ft-wide core of 
limonite- and manganese-stained dense, black massive 
chlorite, a 0.1-ft-wide hanging wall of massive pyrite altered 
to clay, and a 0.5-ft-wide footwall of progressively less 
chlorite-altered granite. This greisen vein pinches and 
swells over at least a 300-ft strike length. Its maximum 
width of 5.0 ft is at sample site 98. 



BENEFICIATION 

Beneficiation tests were conducted on four bulk samples 
at the Bureau's Albany (OR) Research Center. In the first 
test, a composite sample with a calculated head analysis of 
0.06 pet Sn was prepared from equal weights of the four 
samples. The composite was stage ground in rod mills to 
pass 100 mesh, but elaborate steps were not taken to pre- 
vent overgrinding. The sample was then tabled on a slime 
deck of a wet shaking table to produce a concentrate, coarse 
table tailings (those that settled and banded on the table), 
and fine table tailings (those that washed off the table 
without settling). A distinct band of sulfides with minor 
cassiterite formed in the heavy concentrate fraction. The 
metallurgical balance for this test is shown in table 2. The 
concentrate contained 65 pet of the tin at a grade of 0.35 pet 
Sn. 

Although recovery of concentrate was emphasized over 
grade, nearly 35 pet of the tin was lost to the tailings. 
Microscopic examination of the coarse tailings showed that 
most of the cassiterite was liberated and, based on chemical 
analyses, the tin content of the two tailings products was 
low (0.02 pet Sn). However, the tailings represent 90 pet of 
the low-grade sample weight and, thus, tin losses in those 
fractions are relatively high. Recovery may be improved by 
more precise control of the grinding to prevent excessive 
fines and/or by regrinding the coarse tailings and retreating 
them with the rougher fine tailings on equipment more 
suitable to fine-particle treatment than shaking tables. 

In the second test, a split of sample 99, which had a head 
analysis of 0.18 pet Sn (table 1), was stage ground to minus 
100 mesh and tabled, as described previously, to produce a 
rougher concentrate, coarse tailings, and fine tailings. As in 
the first test, good recovery of the heavy, sulfide-rich frac- 
tion was emphasized. The rougher table concentrate was 
then treated in a bulk flotation step to produce a sulfide con- 
centrate float product and a nonfloat tin concentrate. A 
rougher flotation step was done with 0.1 Ib/st potassium 
amyl xanthate as the collector at natural pH of 5.1. The 
froth was very heavily laden with sulfide minerals. A 



Table 2.— Metallurgical balance for tabling composite 
bulk sample' 

Minus 100-mesh wt Analyses, pet Distribution, pet 

product pet Sn S Sn S 

Concrete^ 9.8 0.35 8.68 65.4 69.9 

Coarse tailings 45.9 .02 .31 17.3 11.6 

Fine tailings 44.3 .02 .51 17.3 18.5 

Composite or total . . . 100.0 .05 1.22 100.0 100.0 

'Caleulated eomposite head analysis, percent; 0.04 Cu, 0.48 F, 0.15 Pb 
1.14 S, 0.06 Sn, 0.16 Zn. 
'Additional analyses, percent: 0.07 Cu, 1.56 F, 0.46 Pb, 0.40 Zn. 

Table 3.— Metallurgical balance for tabling and flotation of 
sample 99 

Minus 100-mesh wt Analyses, pet Distribution, pet 

product pet Sn S Sn S 

Rougher table concentrate 12.6 1.05 21.3 93.7 70.5 

Sulfide flotation 

concentrate' 6.5 .25 40.3 11.3 68.7 

Nonfloat tin concentrate' 6.1 1.91 1.10 82.4 1.8 

Cleaner table concentrate' .6 13.9 NA 58.8 NAp 

Cleaner table tailings" . . 5.5 .60 NA 23.6 NAp 

Rougher table coarse 

tailings 39.4 .01 .71 2.8 7.3 

Rougher table fine tailings 48.0 .01 1.76 3.5 22.2 

Composite or total . . . 100.0 .14 3.81 100.0 100.0 

NA Not analyzed. NAp Not applicable. 

Additional analyses, percent: 

'0.15 Cu, 42.9 Fe, 0.67 Pb, 0.85 Zn. 

'2.91 F. 

M.10 F. 

"4.93 F. 

scavenger flotation step with 0.01 Ib/st collector produced a 
very small amount of additional float material that was com- 
bined with the rougher float product for analysis. The 
nonfloat tin concentrate was then retabled in a cleaner step 
to further concentrate the tin. The metallurgical balance for 
the test is shown in table 3. The cleaner table concentrate 
contained 59 pet of the tin at a grade of 13.9 pet Sn. 

As in the first test, tin recovery was relatively low in the 
concentrate, but for different reasons. The cleaner table 
tailings contained an additional 24 pet of the tin at a grade 
of 0.60 pet Sn, and it could be recycled to improve recovery. 
The sulfide flotation concentrate contained 11 pet of the tin, 
some of which conceivably could be cleaned from the sulfide 
concentrate and recovered in the cleaner table operation. 
More elaborate flowsheets and optimum conditions were 
not investigated. 



LODE TIN RESOURCES 



Although the Lime Peak area apparently contains tin- 
mineralized greisen occurrences that are distributed over an 
area in excess of 8 mi^, the grade of these occurrences is too 
low and irregular to allow for adequate definition of in-place 
tin resources. An estimate of total contained metal, 
however, may be made by summing all of the mapped 
lengths and inferred extensions of greisen occurrences, and 
by assuming they continue for one-half their length at depth 
and are mineralized over an average width of 2 ft. At an 
average grade of approximately 0.05 pet Sn and an 
estimated tonnage factor of 11, this calculation suggests 
that approximately 5 MMst of rock containing 5 MMlb Sn is 
present. A slightly higher estimate of 6 to 7 MMlb Sn may 
be made by assuming the greisen occurrences located on the 
ridge north of Bedrock Creek have a slightly higher average 
grade of approximately 0.07 pet Sn. 

This calculation assumes greisen occurrences are con- 
fined to a single 2-ft-wide vein. Clearly, as mentioned 
previously, this is not always the case. For example, the 
northwest-trending greisen zone in the southern portion of 
section 3, north of Bedrock Creek and including sample sites 
13 through 18, appears to be partially mineralized over a 
width of 50 ft along its 3,000-ft strike length. Assuming this 
zone continues for 1,500 ft at depth and is mineralized over 
40 pet of its width for an average grade of 0.03 pet Sn (ap- 
proximately equal to 0.4 x 0.07 pet Sn), this zone may con- 
tain approximately 20 MMst of rock containing 12 MMlb Sn. 
Similarly, if the greisen zone extending northwest from sec- 
tion 3 to section 4, located along the same ridge and exten- 
ding between sample sites 27 and 40, is assumed to be 
mineralized over 40 pet of its 20-ft width and is 3,000 ft long 
and extends to a depth of 1,500 ft, approximately 8 MMst of 
rock containing 5 MMlb Sn may be present. 

Therefore, the resources for the area mapped may be on 
the order of 30 MMst of rock containing 20 MMlb Sn. 
Beneficiation testing suggests that approximately 60 pet, or 
12 MMlb, of this tin could be readily concentrated. It cannot 
be overemphasized, however, that this resource is too low 
grade to be considered economic at the present time. 



PLACER INVESTIGATIONS 



In 1985, gravels located along the upper portions of 
North Fork Preacher Creek were investigated for tin- 
bearing placer deposits. The headwaters of the North Fork 
partially drain the tin greisen occurrences located near 
Lime Peak that were discussed in previous sections of this 
report. Numerous large samples of surface gravels were col- 
lected and gravel types were mapped. Because samples 
were collected from surface exposures, the grade of tin in 
deeper gravels cannot be directly assessed but comparison 
with placer tin deposits elsewhere in Alaska suggests grade 
will increase. 



SURFICIAL GEOLOGY OF NORTH FORK 
PREACHER CREEK 

From headwaters located 2 miles southeast of Lime 
Peak, North Fork Preacher Creek flows northeast toward 



the lowlands of the Yukon Flats (fig. 2). In its lower course, 
beyond approximately 5 miles from the headwaters, the 
creek is mature with a gradient of 1 vertical ft for every 130 
to > 600 horizontal ft. In this area, the creek consists of a 
shallow meandering stream surrounded by a broad alluvial 
plain containing abundant oxbow lakes. For much of its 
lower course, the creek also occupies a generally asym- 
metric (to either the northwest or southeast) valley with 
relatively steep slopes and a flat trough. 

Within 5 miles of its headquarters, the North Fork is a 
juvenile stream with a gradient of 1 vertical ft for every 100 
to < 50 horizontal ft. In this area, it has stretches of broad 
braided stream interspersed with short lengths of poorly 
developed meandering stream. In its upper course the creek 
also occupies and has partially incised the trough of a broad, 
generally U-shaped valley (fig. 8). 

The upper reaches of North Fork Preacher Creek show 
evidence of having been affected by at least two periods of 



10 




Figure 8.— Photograph looking northeast (downstream) 
along the headwaters of the North Fork of Preacher Creek 
from a position near the center of section 10. 

valley glaciation (fig. 9). The older glacier extended at least 
5 miles northeastward along the North Fork to a down- 
valley limit approximately coincident to the northeastern 
contact between the Lime Peak pluton and neighboring 
metasedimentary rocks. The position of the terminal 
moraine of this glacier is indicated by the last of a train of 
large subangular granite lag boulders that were plucked 
from an outcrop approximately 3 miles farther up the valley 
in the central portion of section 35 (fig. 9). A possible rem- 
nant of lateral moraine from the older glaciation is located 
near the lag boulder source at the left limit of the creek in 
the south-central portion of section 35 (fig. 9). 



An outwash plain extends from the terminus of the 
older glacier at least another 5 miles farther down the creek 
(fig. 9). These outwash gravels are locally overlain by 10 to 
15 ft of organic material that has crept off the valley's 
frozen southern slope. Elsewhere along the southern slope, 
the outwash gravels are also overlain by alluvial fan gravels. 
Outwash terraces located 3 to 5 ft above the present creek 
level are common along this stretch of North Fork Preacher 
Creek, especially where recent stream erosion during 
flooding has removed overlying organic material. The out- 
wash gravels are moderately well sorted and locally crudely 
stratified with rounded clasts that are generally less than 
0.5 ft in diameter within a clayey matrix containing only 
minor amounts of grus. These gravels may contain more 
abundant fine intrusive phase and tourmaline-bearing cob- 
bles than other gravels of the area. 

The retreat of the older and the possible advance of a 
younger glacier caused the development of a relatively 
younger outwash plain in the headquarter portion of North 
Fork Preacher Creek. This plain extends from near the 
headwaters of North Fork Preacher Creek to the southern 
terminus of the older glacier (fig. 9). In places along its left 
limit, the plain truncates alluvial fan and till gravels but 
elsewhere, on its right limit, it is overlain by alluvial fan 
gravels. This suggests that the valley is presently cutting to 
the northwest. 

The outwash is somewhat variable, ranging from loose- 
ly packed and poorly sorted grus-rich, to dense, well-sorted 
clay-rich gravels. Cobbles tend to be subangular to 
subrounded and moderately coarse, averaging about 0.4 ft 
in diameter, and are dominantly of intrusive origin. Inci- 
pient podzolic soil development on these gravels is marked 





RSE 




R6E 




R7E 


TION 


1 

,^L«g boulders.. -^ 
Lag boulder eource, ^W/ ^ :-^ 

DD« ,^pM^' 
BB.CC^^Jp Z 


^^^,^ 

j^^ 




1 

1 




LEGEND 
"* ) Terminus ol older glaciation 

^ Terminus of younger glaciation 
^^^„^ Older outwasl) 
^^^^ Younger outwash 
<^ Alluvial fan 
9 Z Placer concentrate sample 
O H Pen concentrate sample 
.-^-'i^'** Outline of Lime Peak pluton 


1 



1 


\ 

1 

1 
1 


TtN 


Scale. 


mile 



Bott odoptad from u S 6 S I 63,360 Circle (C-6 ond C-9) quodronglti 



Figure 9.— Surficial geologic and sample location map for the North Fork of Preacher Creek. 



11 



in places by a loose and weathered grus-rich horizon that 
overlies a thin clay layer, which, in turn, overlies 
manganese- and iron-stained gravel. The outwash plain 
gravels grade into unstratified, coarse, grus-rich colluvium 
along both slopes. 



SAMPLING AND ANALYSES 

Twenty-three gravel samples were collected on or near 
North Fork Preacher Creek (fig. 9). Samples were mostly 
collected from gravel exposures in cutbanks, a few, 
however, were also collected from gravel bars. Samples 
were excavated by hand and loose volumes were measured 
in 5-gal buckets. Where possible, in-place volumes were also 
measured. Most samples were subsequently screened to 
minus 3/8 in and panned to a rough concentrate. A few 
larger samples were also concentrated with a Keene model 
HMJ-1 hydromatic jig,^ and two samples were concentrated 
with a 4-ft-long backpack-style sluice box. In all cases, the 
rough concentrate was further panned in the field to an ap- 
proximately pint-size volume. 

Figure 10 is a flow diagram illustrating how the samples 
were reduced in the laboratory. Concentrates were 
screened to minus 16 mesh, further pan concentrated to a 
standardized volume, examined for mineralogy, and 
weighed. The samples were then analyzed for tin, colum- 

^Reference to specific products does not imply endorsement by the Bureau 
of Mines. 



bium, tantalum, yttrium, and cerium by x-ray fluorescence 
(XRF) and for tungsten using a colorimetric technique. 
Splits of samples with tin concentrations greater than 2 pet 
were subsequently assayed for tin. 

Descriptions, loose volumes, concentrate weights, 
analytical results, and calculated tin grades of placer 
samples collected along North Fork Preacher Creek are 
tabulated in appendix D. Sample volumes range from less 
than 0.1 to 1.0 yd^ and average approximately 0.2 yd^. The 
two larger 1-yd^ samples were concentrated with the 
hydromatic jig. Measured in-place volumes of four samples 
ranged between 2 and 35 pet smaller than the loose volumes 
(table 4). 

Smaller pan concentrate samples were collected from 
drainages feeding North Fork Preacher Creek in order to 
help pinpoint potential sources of the placer minerals (fig. 
9). Samples were shoveled from gravels located either at the 
center of the active channel on smaller creeks or from the 
leading edge of gravel bars on larger streams. Samples 
were concentrated with a 14-in diameter pan that was heap 
filled. Concentrates were further reduced, inspected, and 

Table 4.— Swell factors' calculated from gravel samples 





Sample 


Gravel type 


Volume 


ft' 


_ Swell fac- 




Loose 1 


n-place 


tor, pet 


F 
R 
S 
V 




Older outwash 

• Recent outwash . . . . 

■ Alluvial fan 

.Glacial till 


10.4 
5.5 
6.24 
5.46 


9.4 
5.4 
5.4 
4.0 


10 

2 

15 

35 



'Determined by dividing loose volume by in-place volume and subtrac- 
ting 1. 



Panned field sample 



(Plus 16 mesh) 



Wet screen (16 mesh) 



(Minus 16 mesh) 



Binocular microscopic 
examination 



Tails 



Pan to standard 
volume (10 cm') 



Optical and ultraviolet light 
examination of heavy fraction 



X-ray diffraction of minerals 



Weigh samples 



Shipment for preparation 
and analyses 



Figure 10.— Flow diagram depicting laboratory sample reduction and examination method. 



12 



weighed in the laboratory and subsequently analyzed by the 
same method used on the larger placer samples. 

The heaviest fraction^ of the placer concentrate samples 
are composed of variable amounts of cassiterite, magnetite, 
zircon, monazite, xenotime, topaz, tourmaline (schorl), 
scheelite, garnet, pyrite (or limonite), columbium-bearing 
rutile, and chalcopyrite (table 5). Except for magnetite, all 
of the minerals occur in grains smaller than 1 mm in 
diameter; magnetite occurs in up to 0.5-cm-wide rounded 
pebbles. Cassiterite generally occurs as subrounded to 
subangular, light to dark brown anhedral crystals. 
However, in sample W, some of the cassiterite occurs as 
subhedral to euhedral crystals with minor amounts of at- 
tached greisen. 

Placer concentrate samples collected along North Fork 
Preacher Creek contain between 2,100 ppm and 7.25 pet Sn, 
with grades ranging from 0.002 to 0.04 Ib/yd^ Sn (appendix 
D). Tin grades of outwash gravel samples systematically 
decrease downstream as an inverse function of the square of 
the distance from maximums located both in the Bedrock 
Creek area and near where North Fork Preacher Creek 
crosses the northeastern intrusive contact (fig. 11). Concen- 
trations of tungsten, columbium, tantalum, cerium, and 
yttrium also decrease downstream of the intrusive contact. 

Table 6 shows the results of analyses of panned concen- 
trate samples collected from North Fork Preacher Creek 
and from streams draining into it. Samples collected by Bur- 
ton (1) also are included. Relative tin concentrations of the 
samples have been converted to weight per pan volume 
calculations, as described by Barker (U), in order to 
facilitate comparing the results. Only one of the samples 

'Approximately greater than a specific gravity of 3.5. 



Table 5.— Placer sample concentrate mineralogy^ and relative 
amounts of minerals 

Sample^ W Q P O N L K I E 

Beryl NO NO R? NO NO NO NO NO NO 

Cassiterite A C A M?C A C C A 

Chalcopyrite NO NO R NO NO R NO NO NO 

Garnet T? M NO NO NO NO NO NO NO 

Magnetite . M A C NOG C A C A 

Monazite A A A M A C C C C 

Pyrite or limonite . . NO NO R NO NO R T T NO 

Topaz M M M T M T? NO M NO 

Tourmaline M M C NO M T NO T? NO 

Scheelite M M R T M T NOT T 

Wolframite T? NO NO NO NO NO NO NO NO 

Xenotime M C M NOM M NOM M 

Zircon C A C M A A M C A 

A Abundant. C Common. M Minor. T Trace. 

R Rare. NO None observed. ? Identification uncertain. 

'Determined by optical and X-ray diffraction methods. 

^Samples listed according to location on North Fork Preacher Creek, 
starting near the headwaters. 



(BB) contained significantly greater than 10 mg/pan Sn, 
which is the threshold value for anomalous tin concentra- 
tions determined by Burton (1) for this area. Sample BB was 
collected from residual material overlying greisen adjacent 
to Bedrock Creek (fig. 9). 



PLACER TIN RESOURCES 

The distribution of placer sample tin grades along North 
Fork Preacher Creek (see figure 11) clearly indicates that 
most of the tin in North Fork Preacher Creek is derived 
from two sources. One of these sources is located near the 
northeastern intrusive contact where it is crossed by North 



0.042 



T 



T 



T r 

TRENDS 



T" 



>% 
\ 

UJ 
Q 

< 
CC 

o 



.040- 



.010- 



.008- 



.006- 



.004- 



.002- 



sw 

A Sample DD 
N 



\ A 

These samples ^ 

consisted of very ^, 

loose gravels and are 
likely not representative 

^A 



KEY 



NE 



SAMPLES 
n Older outwQsh 
A Younger outwosh 
O Recent streom olluvium 
A Alluvial fan grovels 

Unknown gravel type 

Till 



\Tin concentrations in 
older outwash samp 



U 
T 
C 



.-3 
\ 



pies 

Tin concentrations in 
younger outwash samples, 
queried where uncertoin 



Col I u V i um 



Position of 
granite contact- 




T 



A« 



»-?—?— ,° 




Sample A 



-r- 

10 



8 



DISTANCE ALONG THE NORTH FORK OF PREACHER CREEK, miles 



Figure 11.— Variation of tin grade along the North Fork of Preacher Creek. 



13 



Table 6.— Analysis and relative tin concentrations of panned 
concentrate samples 

Analysis, ppm Sn cone 

Weight, 
Sample Cb Ce Sn Ta W Y g mQ/pan' 

G 16 66 9 <3 9 9 15.7 0.14 

H 16 315 110 3 10 28 19.24 2.11 

M 17 320 340 3 20 36 20.07 6.82 

P 500 NA 5,000 NA 5,000 NA 2.17 10.85 

AA= <70 NA <100 NA <200 NA 6.40 <.64 

BB' 94 4,600 8,700 16 855 250 17.37 16.0 

CC I 3,400 2,000 36 58 400 19.24 2.5 

I Interference because of Zr. NA Not analyzed. 
'Calculated as decribed by Barker {14) using the formula: 

(ppm value) [1,000 (weight in grams)] 
mg/pan = ^^^^^^ 

^From Burton (1). 

'Represents concentrate from approximately 9 gal of residual material 
lying directly on bedrock. Milligram-per-pan value adjusted accordingly. 

'Represents concentrate from approximately 15 gal of colluvium near 
bedrock. Milligram-per-pan value adjusted accordingly. 



Fork Preacher Creek and is coincident to a hypothesized 
glacial terminal moraine (compare figures 9 and 11). The 
second source of tin lies near the headquarters of North 
Fork Preacher Creek in the Bedrock Creek area. Analytical 
results, however, show low metal grades that do not in- 
dicate a significant placer tin resource under present 
economic conditions. 

Probable large volumes of former low-grade lode tin 
mineralization, eroded from sources near Bedrock Creek, 
are not accounted for by the low placer tin grades found 
during this investigation. Cassiterite identified in both 
placer and greisen samples, however, is very fine grained 
and may be dispersed over a very large area. Additionally, 
much of the fine cassiterite within the gravels likely has 
been concentrated at or near bedrock, so the low grades 
reported from surface gravel samples do not conclusively in- 
dicate a low potential for placer tin deposits. 



SUMMARY AND CONCLUSIONS 



The intrusion at Lime Peak is one of several plutons 
that underlie the White Mountains highland area north of 
Fairbanks, AK. These plutons generally intrude a sequence 
of clastic and carbonate metasedimentary rocks. The 
geology of the Lime Peak pluton is comparable to that of 
many tin-mineralized plutons worldwide. 

Numerous occurrences of tin-mineralized greisen are 
associated with the Lime Peak pluton in the Bedrock Creek 
area southeast of the Lime Peak summit. The greisen is 
composed of complex mineralization-alteration assemblages 
that can be roughly subdivided into two stages based on 
their paragenetic relationship to faulting. Cassiterite 
mineralization is related to the younger of the two 
assemblages, whereas tungsten is associated with the older 
event. 

The average tin grade of 170 samples of greisen from 
the Lime Peak study area is approximately 0.05 pet; 30 
samples from the ridge north of Bedrock Creek define a 
smaller area, with an average tin grade of approximately 
0.07 pet. Beneficiation testing of two bulk greisen samples 
produced concentrates containing 65 and 59 pet of the total 
tin values at grades of 0.35 and 13.9 pet, respectively. 

The lack of outcrops makes determination of mineral- 
ized widths difficult; however, the size of rubble boulders, 
together with the width of occurrences that could be chan- 
nel sampled, suggests that greisen veins are mineralized 
over an average width of approximately 2.0 ft. Individual 



occurrences can rarely be continuously traced for more than 
a few tens of feet; however, discontinous exposures and rub- 
ble distribution suggest several greisen veins may comprise 
zones up to 100 ft wide that can be traced for up to several 
thousand feet along strike. 

The grade of the greisen occurrences is too low and 
variable to allow adequate definition of tin resources. An 
estimate of total contained metal, however, suggests the 
area has a resource potential of 20 MMlb Sn. Beneficiation 
testing suggests that approximately 60 pet, or 12 MMlb, of 
the tin could be readily concentrated. This, however, is con- 
tained in rock that is too low grade to be considered 
economic at the present time. 

Outwash gravels along North Fork Preacher Creek con- 
tain a diverse suite of fine-grained heavy minerals, including 
cassiterite; however, analytical results of surface samples 
show very low metal concentrations that do not indicate a 
significant resource. Two sources of cassiterite are defined 
by the distribution of tin grades in gravels. One source is 
greisen mineralization in the Bedrock Creek area, the other 
is located on North Fork Preacher Creek where it crosses 
the northeastern intrusive contact. Low tin grade in surface 
gravel samples do not account for the former erosion of a 
large volume of tin-mineralized material from the Bedrock 
Creek area and suggest that higher grades may be present 
in gravels closer to bedrock. 



REFERENCES 



1. Burton, P. J., J. D. Warner, and J. C. Barker. Reconnaissance 
Investigation of Tin Occurrences at Rocky Mountain (Lime Peak), 
East-Central Alaska. BuMines OFR 31-85, 1984, 44 pp. 

2. Wahrhaftig, C. Physiographic Divisions of Alaska. U.S. Geo!. 
Surv. Prof. Pap. 482, 1965, 52 pp. 

3. Prindle, L. M. A Geologic Reconnaissance of the Fairbanks 
Quadrangle, Alaska. U.S. Geol. Surv. Bull. 525, 1913, 220 pp. 

4. Foster, H. L., J. Laird, T. E. Keith, G. W. Gushing, and W. D. 
Menzie. Preliminary Geologic Map of the Circle Quadrangle, 
Alaska. U.S. Geol. Surv. Open File Rep. OF 83-170-A, 1983, 32 pp.; 
1 oversize sheet; scale, 1:250,000. 

5. Wilson, F. H., and N. Shew. Map and Tables Showmg 
Preliminary Results of Potassium-Argon Age Studies in the Circle 



Quadrangle, Alaska, With a Compilation of Previous Dating Work. 
U.S. Geol. Surv. Open file Rep. OF 81-889, 1981; 1 oversize sheet; 
scale, 1:250,000. 

6. Barker, J. C. Mineral Deposits of the Tanana- Yukon Uplands. 
A Summary Report. BuMines OFR 88-78, 1978, 26 pp. 

7. Menzie, W. D., H. L. Foster, R. B. Tripp, and W. E. Yeend. 
Mineral Resource Assessment of the Circle Quadrangle, Alaska. 
U.S. Geol. Surv. Open File Rep. OF 83-170-B, 1983, 61 pp.; 1 over- 
size sheet; scale, 1:250,000. 

8. Chapman, R. M., F. R. Weber, and B. Taber. Preliminary 
Geologic Map of the Livengood Quadrangle, Alaska. U.S. Geol. 
Surv. Open File Rep. OF 71-66, 1971, 2 sheets; scale 1:250,000. 

9. Churkin, M., Jr., H. L. Foster, R. M. Chapman, and F. R. 



14 



Weber. Terranes and Suture Zones in East Central Alaska. 
J. Geophys. Res., v. 87, 1982, pp. 3718-3730. 

10. Foster, H. L., F. R. Weber, R. B. Forbes, and E. E. Brabb. 
Re^onai Geology of the Yukon-Tanana Upland, Alaska. Paper in 
Arctic Geology, ed. by M. G. Pitcher. Mem. Am. Assoc. Pet. Geol., 
19. 1973, pp. 388-395. 

11. Taylor, R. G. Geology of Tin Deposits. Elsevier (New York) 
1979, 543 pp. 

12. Hudson, T., and J. G. Arth. Tin Granites of Seward Pennin- 
sula, Alaska. Geol. Soc. America Bull, v. 94, 1983, pp. 768-790. 

13. Gary, M., R. McAfee, Jr., and C. L. Wolf (eds.). Glossary of 
Geology. Am. Geol. Inst., Washington, DC, 1974, p. 313. 

14. Barker, J. C. Reconnaissance of Tin and Tungsten in Heavy 
Mineral Panned Concentrates Along the Trans-Alaskan Pipeline 
Corridor, North of Livengood, Interior Alaska. BuMines OFR 
59-83, 1983, 24 pp. 



15. Carmichael, I. S. E., F. J. Turner, and J. Verhoogan. Igneous 
Petrology. McGraw-Hill (San Francisco), 1974, 737 pp. 

16. Irvine, T. N., and W. R. A. Baragar. A Guide to the Chemical 
Classification of the Common Volcanic Rocks. Can. J. Earth Sci., v. 
8, 1971, p. 523-548. 

17. Nockolds, S. R. Average Chemical Compositions of Some Ig- 
neous Rocks. Geol. Soc. America Bull., v. 65, 1954, pp. 91-108. 

18. Thorton, C. P., and 0. F. Tuttle. Chemistry of Igneous 
Rocks- 1, Differentiation Index. Am. J. Sci., v. 258, 1960, pp. 
664-684. 

19. Rose, A. W., H. E. Hawkes, and J. S. Webb. Geochemistry in 
Mineral Exploration. Academic (San Francisco), 1979, 657 pp. 

20. Deer, W. A., R. A. Howde, and J. Zussman. An Introduction to 
the Rock-Forming Minerals. Longman Group Ltd., London, 1966, 
528 pp. 



15 



APPENDIX A.— DESCRIPTION OF IGNEOUS ROCKS MAPPED NEAR LIME PEAK 



Two major plutonic phases and numerous dikes of analyzed samples of this phase have differentiation indexes* 

various compositions were mapped near Lime Peak (figure of 92, indicating a high degree of fractionation, and two of 

3, main text). Descriptions of each rock type follow. the samples contain minor amounts of normative corum- 

A coarse-grained intrusive phase (Tgc) underlies most dum. Trace element analyses indicate this phase is relatively 

of the higher elevations of the Lime Peak area and forms enriched in boron, beryllium, fluorine, lithium, tin, uranium, 

tors along ridges. This unit comprises medium- to coarse- and thorium compared to the average granite as compiled 

grained seriate to porphyritic biotite granite and contains by Rose (19) (table A-1). 

modal compositions between 30 and 38 pet quartz, 40 and 45 The second most abundant lithology, a relatively finer 
pet orthoclase, 14 and 20 pet plagioclase, and 3 and 7 pet grained, porphyritic granite (Tgp), underlies much of 
biotite. Trace to minor amounts of fluorite and black tour- Bedrock Creek and the surrounding hillsides. This unit is 
maline fill miarolitie cavities in this rock, and zircon and characterized by a variable texture, but is most commonly 
other high-refractive index minerals are common inclusions porphyritic with a hypidiomorphic seriate groundmass and 
in biotite. Plagioclase, quartz, and biotite typically form a phenocrysts of anhedral orthoclase and quartz. Fine- 
granular groundmass within which are larger anhedral grained to moderately coarse grained equigranular varieties 
twinned orthoclase crystals. of this unit are also locally present. 

Major-oxide analyses of four samples of the coarse- Samples of this rock contain modal compositions between 

grained granite indicate subaluminous^ (isy to 40 and 50 pet quartz, 29 and 34 pet orthoclase, 10 and 20 pet 

metaluminous^ (15) and subalkaline (16) compositions that plagioclase, 3 to 7 pet biotite, and 1 to 3 pet museovite, as 

are generally comparable to that of average biotite alkali well as trace to minor amounts of tourmaline, fluorite, 

granite reported by Noekolds (17) (table A-1). All four topaz, zircon, monazite, and xenotime. Quartz typically 

shows undulose to polyerystalline extinction and orthoclase 

■Molecular porportion of AI2O3 is approximately equal to that of the sum of commonly has micrographic intergrowths of plagioclase as 

Na.OandK.O,butislessthanthesumofCaO,NaAandK.O ^ jj j j especially near phenocryst margins, 

^Italic numbers m parentheses refer to items m the list of references . , '. . ^ -^ , . . '^ \. .^^ 

preceeding this appendix. microgranophyric mtergrowths with quartz. Muscovite ex- 

^Molecular proportion of AI2O3 exceeds that of the sum of NazO and K2O, 

but is less than the sum of CaO, Na20, and K2O. ""Sum of normative quartz, orthoclase, and albite (IH). 

Table A-1— Composition of Lime Peak pluton samples 

Rock type Tgc Tgp Tgm Tr p^^ b^q /^^ gran- 

Sample' 10 19 54 21218 58 63 89 102 104 20730 50 (17) ite (79) 

MAJOR OXIDE ANALYSES,' wt pet 

SiOj 74.00 74.50 75.50 75.00 75.70 77.30 77.00 77.40 76.50 74.00 71.50 75.01 NAp 

AljOj 12.70 12.30 12.30 12.30 12.40 12.10 12.30 12.40 12.20 13.60 14.80 13.16 NAp 

FeA 2.50 2.20 .26 2.15 .18 .27 .43 .12 .22 1.20 .90 .94 NAp 

PeO NA NA 1.94 NA 1.52 1.83 1.37 1.68 1.58 NA NA .88 NAp 

MgO 15 .10 .19 .05 .04 .09 .05 .03 .03 ND ND .24 NAp 

CaO 85 .80 .76 .85 .67 .86 .45 .68 .80 .50 .70 .56 NAp 

NajO 2.70 2.70 1.90 3.00 2.10 2.10 2.00 2.20 2.10 4.40 5.80 3.48 NAp 

KjO 5.70 5.80 4.60 5.50 4.50 4.60 4.90 4.20 4.40 4.80 4.40 5.01 NAp 

TiO^ 15 .10 .18 .05 .05 .05 .09 .03 .04 ND ND .11 NAp 

PjOs 04 .03 .08 .03 .08 .08 .06 .07 .06 .04 .02 .07 NAp 

LOI .75 .76 NA .51 NA NA NA NA NA .58 .54 .54 NAp 

Total 99.54 99.29 97.71 99.44 97.24 99.35 98.65 98.81 97.93 99.12 98.66 99.90 NAp 

NORMATIVE MINERAL COMPOSITION,' wt pet 

Albite 23.16 23.20 16.45 25.67 18.27 17.89 17.15 18.84 18.14 37.78 50.02 29.48 NAp 

Anorthlte 4.00 3.83 3.32 3.89 2.88 3.77 1.87 2.95 3.65 2.25 1.38 2.06 NAp 

Apatite 09 .07 .19 .07 .19 .19 .14 .16 .14 .08 .05 .26 NAp 

Corundum 65 .20 3.08 ND 3.13 2.31 3.70 3.20 2.73 .36 ND 1.16 NAp 

Diopside ND ND ND .13 ND ND ND ND ND ND ND ND NAp 

Enstatite 38 .25 3.61 .06 2.74 3.18 2.17 3.05 2.77 1.22 ND .60 NAp 

Hematite ND .61 ND .46 ND ND ND ND ND 1.22 .92 ND NAp 

llmenite 29 .19 .35 .10 .10 .23 .17 .06 .08 ND ND .32 NAp 

Magnetite 2.06 1.47 .39 1.60 .27 .39 .63 .18 .33 ND ND 1.36 NAp 

Orthoclase 34.12 34.81 27.82 32.87 27.35 27.36 29.35 25.12 26.55 28.78 26.50 29.64 NAp 

Quartz 35.00 35.36 44.80 35.13 45.08 44.68 45.46 46.44 45.59 29.51 20.30 34.07 NAp 

Wollastanite ND ND ND ND ND ND ND ND ND ND .85 ND NAp 

CONCENTRATION,' ppm 

B 100 100 100 200 100 200 100 100 100 200 100 NAp 10 

Ba 200 <200 600 70 90 200 100 200 20 <20 <200 NAp 840 

Be 10 7 40 30 70 30 30 10 20 20 40 NAp 3 

Cb <50 <50 <50 c50 <50 51 <50 57 <50 <50 80 NAp 20 

F 980 1,500 1,800 570 3,900 2,900 1,200 5,700 4,800 930 1700 NAp 810 

LI 50 44 37 100 61 27.5 64 97 53 NA 25 NAp 40 

Rb 210 270 390 240 480 420 370 590 510 NA 330 NAp 276 

Sn 7 7 <5 <5 <5 <5 <5 <5 7 NA 48 Nap 3.0 

Sr 3 3 46 <10 <10 20.8 <10 <10 <10 <10 <10 Nap 100 

Ta <100 <100 <100 <100 <100 100 <100 <100 <100 <100 <100 NAp 3.5 

Th 70 60 75 60 70 85 55 75 75 40 35 NAp 20 

U 5.3 7.8 4.3 7.8 11 8.5 6.6 14 14 4.8 12.0 NAp 3.9 

W <5 <5 <5 <5 8 6 <5 6 <5 NA <5 NAp 1.5 

Zr <30 30 200 <30 550 210 170 92 120 <30 <30 NAp 175 

Rock types: Tgc Coarse-grained granite. Tgp Porphyritic granite. Tgm Muscovite granite. Tr Rhyollte. 

BAG Biotite alkali granite. NA Not analyzed. ND Not detected. NAp Not applicable. 

'Sequentially numbered generally from northeast to southwest on figure 3 of main text. Samples with 5-dlglt numbers were collected from outside 
the area shown in figure 3. Sample 21218 Is from near the pluton's southern contact in the southeast quarter of T 9 N, R 4 E; sample 20730 is from 
a small tongue of granite that extends south from the pluton In the south-central portion of T 9 N, R 4 E (see Burton (/) for location). 

'Normalized to 100 pet. 

'Ba, Cb, and Ta determined by XRF; B by emission spectrography; W, U, and F by specific chemical methods; Th by radiometric techniques; Zr 
and Be by ICP methods; and Rd, Sr, LI, and Sn by AA. 



16 



hibits anomalously high mid-third-order birefringence colors 
and clear to pale-green pleochroism indicative of a high-iron 
composition (20), and occurs both in patches associated with 
biotite and disseminated in the matrix. Topaz occurs as 
subhedral to anhedral crystals within the groundmass and is 
interpreted as primary. 

Major-oxide compositions of five samples of the por- 
phyritic granite (Tgp) indicate subalkalic and markedly 
peraluminous compositions with relatively lower total- 
alkali, AI2O3, Ti02, and MgO concentrations than those of 
the coarse-grained granite (Tgc). Differentiation indexes of 
samples of the porphyritic granite, ranging between 89 and 
91, are also somewhat less than those of the coarse-grained 
granite. In contrast, however, the porphyritic granite is 
relatively enriched in Si02 and P2O5 and has greater than 2 
pet normative corundum. The porphyritic granite is also 
enriched in uranium, thorium, rubidium, fluorine, and 
possibly columbium, beryllium, zirconium, and tungsten, 
and contains higher uranium-to-thorium and rubidium-to- 
strontium ratios relative to samples of the coarse-grained 
granite and to an average granite composition. 

Dikes of porphyritic rhyolite, andesite, and 1am- 
prophyre are also common in the Bedrock Creek area. 
These dikes range from a few feet to several tens of feet 
wide, and typically trend northwest, cutting the two more 
abundant intrusive phases. The rhyolite is composed of 
subequal amounts of subhedral to euhedral quartz, or- 
thoclase, and albitic plagioclase and minor irregularly 
shaped biotite phenocrysts in a fine matrix of quartz, or- 
thoclase, and muscovite (1). Phenocrysts make up 60 pet of 



this rock, and fluorite occurs rarely in miarolitic cavities. 
Major oxide analyses of one sample (50) of the rhyolite in- 
dicate a peraluminous and alkalic composition with a dif- 
ferentiation index of 96 (table A-1). One andesite dike was 
mapped in the east fork of Bedrock Creek, and andesite rub- 
ble is common on the south flank of the Lime Peak summit. 
The andesite is dark green to gray and commonly contains 
phenocrysts of plagioclase feldspar. Two lamprophyre dikes 
were also mapped in the east fork of Bedrock Creek; this 
rock is dark green to black and contains no obvious 
phenocrysts. Neither the andesite nor lamprophyre were ex- 
amined optically or analyzed for major oxide composition. 

The major oxide composition of a sample (20730) of 
medium-grained equigranular muscovite granite (Tgm) 
from the southern portion of the Lime Peak pluton is in- 
cluded in table A-1. Although this rock is not present in the 
area of detailed mapping, its analysis is included for com- 
parative purposes. Analysis indicates a metaluminous and 
sodium-enriched subalkalic composition with a differentia- 
tion index of 96. This rock appears to be the most evolved 
plutonic phase of the Lime Peak pluton. Where observed in 
one thin section, the muscovite granite was composed of ap- 
proximately 40 pet quartz, 30 pet plagioclase, 25 pet ortho- 
elase, 4 pet muscovite, and variable but generally minor 
amounts of fluorite, topaz, and blue tourmaline. Tourmaline 
and fluorite fill miarolitic cavities, and plagioclase occurs as 
euhedral laths surrounded by anhedral quartz, orthoelase, 
and topaz, and subhedral muscovite crystals. The muscovite 
is similar to muscovite in samples of the porphyritic granite. 



17 



APPENDIX B.— DESCRIPTION OF GREISEN OCCURRENCES SAMPLED NEAR LIME 

PEAK 



Approximately 30 different minerals have been iden- 
tified in greisen samples collected near Lime Peak. These 
minerals and their paragenetic relationships are listed in 
figure 6 of the main text. Based on their paragenetic rela- 
tionship to faulting, two alternation-mineralization stages 
appear to be represented. Each of these stages is discussed 
in the following. 

The paragenetically older (stage 1) mineral assemblage 
is best exposed, and is largely confined to the East Fork of 
Bedrock Creek area (fig. 4). Samples containing similar 
alteration minerals, however, have also been found on the 
hillside north of Bedrock Creek. This greisen assemblage is 
relatively barren of tin. Stage 1 may actually represent 
several separate or paragenetically overlapping mineral 
suites; however, all of the vein sets are cut by faults or frac- 
tures associated with later stage 2 alteration. 

Most characteristically, stage 1 veins sets trend west- 
northwest and comprise 3- to > 25-ft-wide zones containing 
three to six thin veins per foot (fig. 4). Locally, however, 
veins may obtain thickness of up to 0.5 ft or may crisscross 
in a stockwork fashion (sample 47). The veins may also be 
very irregular and poddy (sample 119). 

Stage 1 veins are typically composed of relatively coarse 
grained muscovite, quartz, and topaz with lesser purple 
fluorite, molybdenite, and a columbium-tungsten-iron 
mineral, tentatively identified as wolframoixiolite (fig. 6). 
The muscovite is quite distinctive and contains anomalously 
high third-order birefringence colors, and clear to pale 
green pleochroism similar to that found in the porphyritic 
and muscovite granites, and similarly indicates a high-iron 
content^ (20).^ In places along- Bedrock Creek, especially 
near sample site 126, the muscovite-nch veins parallel up to 
1-in-wide veins of quartz, albite, green fluorite, and green 



'Microprobe analysis indicates the green muscovite has a general composi- 
tion of K[(Fe)2Al]lAl3 30io(OH)2. 

^Italic numbers in parentheses refer to items in the list of references 
preceding appendix A. 



300 350 400 450 500 550 600 



15 


^ n = 50 






10 


- 




- 


5 


- 


y 


1 






r n 



muscovite. The two vein sets may be contemporaneous; 
however, in a thin section of sample 126, the quartz-albite 
vein was observed to be cut by a more typical stage 1 veinlet 
of quartz and topaz. 

Analysis of fluid inclusions^ in quartz and topaz of the 
stage 1 vein set indicates a wide range of homogenization 
and decrepitation temperatures, with homogenization to 
either a liquid or a vapor (fig. B-1). These results suggest the 
fluid was boiling at the time that these minerals were 
precipitated. Corresponding last melting temperature 
measurements cluster near -25° C, but range as high as 
-6° C, indicating a range of salinities between 10 and 43 
equivalent wt pet NaCl. 

The paragenetically younger (stage 2) alteration- 
mineralization assemblage at Lime Peak consists dominant- 
ly of quartz, chlorite, and sericite, with locally abundant 
topaz, fluorite, tourmaline, and pyrite. The pyrite locally 
contains inclusions of bismuth minerals, (bismuthinite and 
native bismuth). In addition, sphalerite, galena, 
chalcopyrite, cassiterite (see figure 7), columbium-bearing 
rutile (fig. B-2), and other fine-grained accessory minerals 
are sometimes present. Most of these minerals occur as ran- 
dom clots, small veins, and scattered grains, usually within 
the chlorite matrix. Late-stage alteration minerals include 
iron, manganese, and lead oxide minerals, kaolinite, an 
unidentified calcium-iron-uranium mineral, and malachite 
and chrysocolla (fig. 6). Sericite in the stage 2 assemblage is 
distinguished from muscovite of the stage 1 assemblage by 
its fine-grained nature, lack of pleochroism, and relatively 
lower birefringence colors, and is probably of the low-iron 
variety {20). Tourmaline exhibits anomalous purple to blue 
pleochroism. Chlorite has a light green to yellow 
pleochroism and exhibits high first-order birefrigence colors 
indicative of a high-iron, low-silica composition (16).'* 

'Analyses by S. Masterman, graduate student, University of Alaska. 
■•Microprobe analyses indicate a composition of approximately 
(F'eo.87Alo.,3)4(Alo.4.Si,,,,),0,„(OH)3. 




1 1 

n = 31 

n 1 1 1 r 




1 














1 1 1 1 1 1 1 













KEY 

LH Homogenize to o liquid 
B Homogenize to a gas 
C Decrepitate 
H CO, -rich inclusions 



1 r 

n = 26 



n II n 1 1 n 1 1 1 1 m 



150 200 250 300 350 

HOMOGENIZATION TEMPERATURE. » C 



-5 -10 -15 -20 

LAST MELTING TEMPERATURE, 



Figure B-1.— Results of fluid inclusion analyses; (A) stage 1 vein and (B) stage 2 vein. 



18 




Figure B-2.— SEM micrograph of crystals of columbium- 
bearing rutile (white) in a chlorite (gray) and quartz (black) 
matrix. 



Where most pervasively developed, the younger (stage 
2) greisen assemblage consists of a mass of chlorite and 
quartz intergrown with, and partially replacing, sericite, 
topaz, fluorite, and tourmaline. These minerals may be 



developed around a central open-space-filling veinlet of 
similar composition. Locally, for example at sample site 89, 
the wallrocic is so thoroughly recrystallized that vugs lined 
with quartz, chlorite, and fluorite are present. Pervasive 
greisen alteration is progressively developed from a less 
altered, porphyritic-appearing rock containing partially 
replaced relict anhedral quartz grains in a matrix-of fine- 
grained quartz, chlorite, sericite, fluorite, and tourmaline. 
Chlorite and sericite replace biotite and feldspars; chlorite 
replaces sericite as the alteration progresses. 

In many altered specimens or outcrops, the alteration 
zoning is asymmetric. Where the zoning is asymmetric, the 
most pervasively altered rock, which comprises massive, 
penetratively deformed chlorite and angular quartz 
fragments, is truncated by a planar slickensided surface and 
undoubtedly represents gouge adjacent to a fault. The abun- 
dance of greisen-altered float with slickensided surfaces in- 
dicates that much of the paragenetically younger (stage 2) 
greisen is localized along faults. 

Analysis of fluid inclusions in quartz from a vein within 
the quartz-chlorite greisen indicates a relatively narrow 
range of homogenization temperatures, with an average 
value of 220° C (fig. B-1). In contrast, corresponding last 
melting temperature measurements exhibit a wide range of 
values from 0° to -24° C. The range in last melting 
temperatures suggests that this greisen assemblage was 
deposited under a wide range of salinities corresponding to 
to 40 equivalent wt pet NaCl. 



19 



APPENDIX C— RESULTS OF ANALYSES OF ROCK SAMPLES COLLECTED FROM THE 

LIME PEAK AREA 

Table C-1.— Results of quantitative geochemlcal analyses' of rock samples 



Sample^ Type 



Length' 
or area 



Analyses, ppm 



Ag 



Au 



Sn 



U 



W 



CbjOs 



Field description' 



.G NAp . 

.Ch 2 ft .. 

.G 150 ft^ 

.G NAp . 

.C 3 ft .. 



6 G >0.5 ft 

7 G 125 ft^ . 

8 G 300 ft^ , 

9 G 300 ft^ , 

11 G 300 ft' . 



12 



13 
14 

15 
16 
17 

18 
20 
21 

22 
23 
24 

25» 

26 
27 
28 
29 
30 

31 
33 



38 
39 

40 
41 
42 
43 
44 
46 
47 



48 

49« 

50 
51 
52 
53 
55 
56 
57 
59 
60 

61 
62 

64 



65 



.NAp 



.C 5 ft . 

.G ........60 ft' 



.4 ft . 
.NAp 
.60 ft 



.G 100 ft . 

.G NAp .. 

.G <0.8 ft 

.G 200 ft . 

-G 30 ft' .. 

.G 60 ft' .. 

.G NAp .. 



.G 1 ft . 

.G NAp 

.C 20 ft 

.G 20 ft 

.G 60 ft' 



34 C 

35 G 

36 C 

37 C 



.30 ft' 
.NAp 

.NAp 
.NAp 
.NAp 
.NAp 



.G 30 ft 

.G 50 ft 

.5 ft 



.C 0.4 ft 



.NAp 
.3 ft 
.NAp 
.NAp 
.NAp 



.NAp 
.NAp 



.G NAp . 

.G 20 ft' . 

.G 25 ft' . 

.G NAp . 

.G 900 ft' 

.G 60 ft' . 

.C NAp . 

.0 4 ft .. 

.C 10 ft . 



.NAp 
.1 ft 

.NAp 



■ NAp 



LD 
=0.3 
^8 
2.9 


LD 
LD 
LD 
LD 


310 

300 

1,010 

280 


1.0 


LD 


380 


5.0 


LD 


1,100 


1.5 
4.1 
2.8 
2.0 


LD 
LD 
LD 
LD 


730 
200 
220 
950 



1.1 



LD 



300 



28 


6 


LD 


5.9 


LD 


LD 


8.5 


8 


100 


12 


16 


66 


14 


36 


LD 


8.8 


12 


LD 


18 


6 


LD 


12 


LD 


LD 


9.4 


LD 


LD 


25 


LD 


LD 



7.6 



LD 



1.6 


LD 


120 


10 


LD 


LD 


4.1 


LD 


340 


19 


LD 


LD 


1.6 


LD 


310 


11 


LD 


LD 


'.8 


LD 


1,200 


14 


LD 


LD 


^4 


LD 


430 


19 


LD 


LD 


1.0 


LD 


860 


16 


6 


LD 


LD 


LD 


130 


8.5 


LD 


LD 


=0.6 


'0.007 


370 


17 


LD 


LD 


1.7 


LD 


230 


30 


10 


LD 


2.4 


LD 


210 


33 


12 


69 


^4 


LD 


480 


37 


10 


LD. 


36.4 


ND 


99 


NA 


16 


LD 


NA 


NA 


170 


NA 


6 


LD 


1.9 


.025 


850 


22 


14 


LD 


1.4 


LD 


730 


17 


LD 


LD 


^8 


.024 


670 


15 


8 


LD 


1.5 


=.007 


940 


27 


8 


LD 


3.10 


LD 


1,000 


31 


6 


LD 


10.8 


LD 


200 


42 


200 


LD 


17.5 


.016 


35 


<.5 


20 


LD 


17.8 


LD 


800 


18 


60 


LD 


LD 


.019 


600 


14 


12 


LD 


LD 


LD 


530 


20 


20 


LD 


2.1 


LD 


100 


9.8 


32 


LD 


5.1 


LD 


400 


8.7 


6 


LD 


20.6 


LD 


3,800 


36 


LD 


LD 


1.4 


LD 


120 


8.5 


10 


LD 


LD 


LD 


300 


NA 


LD 


68 


LD 


=.007 


1,030 


9.4 


12 


LD 


2 


LD 


620 


15 


6 


LD 


2.1 


=.009 


54 


13 


LD 


79 


1.3 


LD 


10.4 


15 


160 


LD 


LD 


.038 


6 


11 


14 


LD 


6.3 


LD 


660 


22 


16 


LD 


NA 


NA 


120 


30 


6 


LD 


2 


LD 


220 


6.9 


8 


LD 


LD 


LD 


280 


15 


6 


LD 


1.5 


=.007 


220 


15 


12 


LD 


LD 


.045 


200 


19 


LD 


LD 


8.5 


LD 


150 


51 


LD 


LD 


LD 


LD 


2,700 


14 


10 


LD 


LD 


LD 


490 


16 


10 


LD 


.5 


LD 


210 


17 


8 


LD 


1.6 


LD 


180 




6 


LD 


LD 


LD 


210 


13 


32 


LD 


3.5 


LD 


240 


19 


900 


56 
10 
19 
20 


NA 


NA 


120 


NA 


30 


15 



See explanatory notes at end of table. 



Mn-stalned coarse granite. 

Chlorite grelsen. 

Chlorlte-quartz grelsen. 

Quartz-chlorlte-serlcite-fluorlte 
grelsen. 

Chlorlte-quartz llmonltic grelsen 
boulder. 

Chlorite-quartz-muscovlte-fluorlte- 
tourmallne-chalco-pyrlte grelsen. 

Chlorite grelsen. 
Do. 
Do. 

Chlorite-sericlte-quartz-fluorlte-topaz- 
pyrlte-chalcopyrite grelsen. 

Grelsen boulder with open-space- 
filling quartz-muscovlte-fluorlte- 
topaz vein. Open spaces are filled 
with chlorite. 

Chlorite-altered coarse granite. 

Chlorite-altered granite and quartz 
veins. 

Massive chlorite grelsen. 

Massive limonitlc chlorite grelsen. 

Massive chlorite and chlorite- 
altered granite. 

Limonitlc quartz-chlorite grelsen. 

Chlorite-altered granite. 

Serlcite-quartz-chlorite-pyrite-fluorite- 
greisen. 

Chlorlte-quartz greisen. 

Quartz-chlorite Mn-stalned greisen. 
Do. ^ 

Chalcopyrite-pyrite-arsenopyrite- 
bearlng limonitlc greisen. 

Fluorite-bearlng greisen. 

Mn-stalned quartz-chlorite greisen. 

Chlorlte-quartz-sericite grelsen zone. 

Quartz-chlorite grelsen. 

Quartz-chlorite and massive chlorite 
greisen. 

Cnlorite-quartz greisen. 

Quartz-chlorite-sericite-fluorite 
greisen. 

Quartz-chlorite-fluorite greisen. 
Do. 

Chlorite-sericite-quartz greisen. 

Chlorite-sericlte-quartz altered 
granite. 

Chlorite greisen. 

Chlorite-sericite-altered granite and 
massive chlorite grelsen. 
Do. 

Chlorite-serlclte altered granite. 

Muscovite-sericite-topaz greisen. 

Massive chlorite greisen. 

Chlorite grelsen. 

Quartz-green fluorite pegmatite. 

Stockwork quartz-muscovite-topaz- 
fluorite veins with trace molyb- 
denite. 

Stockwork quartz-fluorite-chlorite- 
velns. 

Limonitlc pyrite-chalcopyrite-bearing 
chlorite grelsen. 

Biotite-tourmaline pegmatite. 

Chlorite-sericite-quartz greisen. 

Sericite-chlorite-quartz greisen. 

Mn-stalned quartz-chlorite greisen. 

Chlorite grelsen. 
Do. 

Chlorlte-quartz greisen. 

Quartz-chlorite greisen. 

Quartz-chlorite altered zone along 
fault. 

Pervasively chlorite-altered granite. 

Quartz-chlorite altered granite 
adjacent to fault. 

Quartz-sericile-py rite-tourmaline- 
altered granite cut by quartz- 
tourmaline-sericite veins. 

Dense chlorite greisen. 



20 



Table C-1.— Results of quantitative geochemical analyses' of rock samples— Continued 



Sample' Type 



Length' 
or area 



Analyses, ppm 



Ag 


Au 


Sn 


U 


W 


CbjOs 


NA 


NA 


79 


NA 


80 


22 


NA 


NA 


220 


NA 


8 


17 


NA 


NA 


210 


NA 


8 


LD 


NA 


NA 


62 


NA 


4 


LD 


NA 


NA 


595 


NA 


5 


LD 


=0.5 


LD 


15.1 


7.5 


LD 


LD 


LD 


LD 


120 


1.7 


LD 


LD 


6.6 


LD 


300 


8.3 


LD 


LD 


LD 


=0.009 


510 


12 


10 


LD 


^4 


LD 


750 


7.3 


12 


LD 


2.9 


=.012 


100 


11 


LD 


LD 


9.2 


=.008 


210 


33 


10 


<50 


3.8 


.011 


1,050 


17 


6 


52 


\7 


LD 


170 


13 


6 


LD 


'.9 


=.007 


12.6 


13 


6 


62 


1.1 


LD 


580 


27 


24 


LD 


^8 


.125 


5 


85 


LD 


LD 


1.1 


LD 


190 


13 


8 


LD 


LD 


.021 


100 


28 


LD 


77 


LD 


LD 


LD 


8.1 


LD 


LD 


LD 


LD 


7.9 


=.8 


LD 


LD 


^3 


.007 


3,400 


60 


6 


LD 


LD 


=.010 


250 


11 


6 


52 


LD 


LD 


270 


17 


LD 


LD 


LD 


LD 


24.9 


9.3 


LD 


LD 


LD 


=.007 


530 


20 


LD 


LD 


LD 


LD 


230 


60 


LD 


62 


LD 












LD 


=.009 


36 


5.7 


6 


LD 


1.2 


=.008 


810 


32 


6 


LD 


=.3 


LD 


250 


7.8 


LD 


LD 


5.4 


LD 


1,090 


17 


LD 


LD 


=.7 


LD 


380 


20 


LD 


LD 


5.4 


.092 


520 


24 


6 


58 


1.2 


.219 


460 


35 


LD 


54 


5.2 


.284 


330 


26 


LD 


52 


^8 


.080 


1,110 


28 


LD 


LD 


1.2 


LD 


350 


30 


LD 


60 


2.8 


=.008 


500 


23 


LD 


LD 


1.6 


=.011 


380 


41 


6 


72 


4.1 


=.010 


68 


26 


6 


LD 


9.1 


LD 


270 


19 


LD 


78 


16.6 


=.013 


200 


93 


LD 


LD 


1.8 


=.007 


58 


22 


14 


63 


1.7 


LD 


210 


20 


LD 


110 


6.8 


=.007 


280 


25 


LD 


93 


LD 


LD 


39 


22 


LD 


LD 


=.3 


.032 


120 


17 


1,000 


100 


LD 


.067 


11.7 


22 


3,200 


80 


LD 


=.008 


53 


12 


20 


140 


*0.6 


=.007 


150 


22 


24 


200 


8.6 


LD 


870 


19 


LD 


70 


6.6 


=.008 


210 


30 


LD 


160 


1.8 


=.007 


340 


12 


20 


110 


4.6 


LD 


1,060 


17 


10 


140 


LD 


=.008 


87 


12 


6 


LD 


, 205.8 


.100 


1,050 


8.9 


ND 


LD 


NA 


NA 


590 


NA 


LD 


LD 


23.4 


LD 


660 


16 


LD 


LD 


9.4 


=.010 


670 


18 


6 


LD 


91.1 


LD 


3,700 


44 


14 


LD 


LD 


LD 


17 


8.3 


6 


LD 



Field description" 



66 . 

67 . 

68 . 

69 . 

70 . 

71 . 

72 . 

73 . 

74 . 

75 . 

76 . 

77 . 

78 . 

79 . 

80 . 

81 . 

82 . 

83 . 

84 . 

85 . 

86 . 

87 . 

88 . 

91 . 

92 . 

93 . 

94 . 

95 . 

96 . 

97 . 

100 
101 
103 
105 
106 
107 
108 
109 
110 
111 
112 
113 
114 
115 
116 
117 
118 

119 
120 

121 
122 

123 
124 

125 

126 



127 
128 
129 

130 
131 

132 



133 

134 
135 



136 

137 



.C 5 ft . 

.C 5 ft . 

.C 7 ft . 

.C 7 ft . 

.C 2.5 ft 



.C .. 
.G .. 
.G .. 
.G .. 
.G .. 
.G .. 
.G 1,000 ft 



.4 ft 
.NAp 
.NAp 
.NAp 
.NAp 
.NAp 



30 ft' 

G 30 ft' . 

G NAp . 

G NAp . 

G NAp . 

G 100 ft' 

G 150 ft' 

G NAp . 

G NAp . 

C NAp . 

G NAp . 



.G 5,000 ft' 

.G NAp ... 

.G 800 ft' .. 

.G 1,000 ft' 



.0 6 ft . 

.Ch 2 ft . 

.Ch 0.5 ft 



■ Ch 
.Ch 
.Ch 
.Ch 
.Ch 



.0.8 ... 

.2.5 ... 

.1 ft .. 

.3 ft .. 
, . 2 f t . . 

.G »0.4 ft 

.Ch 6 ft .. 

.Ch 2 ft .. 

.Ch 2.5 ft . 

.Ch 0.7 ft . 



.Ch 
C 



.3 ft 
.NAp 



. C »0.4 ft 



.C 
.C 
■ Ch 



."12 ft 

.10 ft. . 

..0.3 ft . 



.Ch 0.5 ft 



.G . 
.Ch 



.Ch .... 
.G 



.Ch 
.Ch 



.NAp 
.3 ft . 

.0.8 ft 
.NAp 

.0.5 ft 
.3 ft . 



.Ch 1 ft . 

.C 0.4 ft 



.H . 
.H . 
.Ch 



.1 ft 
.1 ft 
.4 ft 



.C "25 ft 

.Ch 0.7 ft . 



.Ch 



.2 ft 



.Ch 0.2 ft 

.Ch 3.5 ft 

-C 16 ft 



.C 0.3 ft 

.C 0.3 ft 



LD 



LD 



7.6 



6.7 



LD 



LD 
LD 


LD 
LD 


11.4 
67 


16 
11 


60 
28 


LD 
LD 


LD 


LD 


270 


14 


LD 


LD 


LD 


LD 


300 


11 


280 


LD 



Dense chlorite greisen. 

Do. 

Do. 

Do. 

Do. 
Mn-stained, chlorite-altered granite. 
Chlorite-pyroxene skarn. 
Chlorite-altered granite. 
Quartz-chlorite greisen. 

Do. 
Mn-stained chlorite greisen. 
Quartz-chlorite greisen. 
Quartz-chlorlte-fluorite greisen. 

Do. 
Quartz-chlorite greisen. 

Do. 

Do. 

Do. 

Do. 
Incipiently chlorite-altered granite. 

Do. 
Massive chlorite greisen. 
Vuggy quartz-chlorite greisen with 
open space filled with fluorite. 
Quartz-chlorite greisen. 

Do. 

Do. 
Quartz-chlorite fluorite greisen. 

Mn-stained, chlorite-altered granite. 
Quartz-chlorite greisen. 
Moderately developed chlorite 
greisen. 
Quartz-chlorite-green fluorite greisen. 
Quartz-chlorite greisen. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Topaz-muscovite greisen. 
Quartz-chlorite greisen. 
Do. 
Do. 
Do. 
Quartz-topaz vein with topaz- 

muscovite-fluorite-altered selvage. 
Topaz-muscovite-fluorite greisen. 
Zone of thin muscovite-topaz(?) 

quartz veins. 
Topaz-muscovite-fluorite greisen. 
Muscovite-rich greisen adjacent to 
fault. 

Minor quartz-chlorite-greisen zone. 
Quartz-chlorite greisen cut by thin 

muscovite-quartz veins. 
Chlorite greisen with chlorite altera- 
tion selvage. 
Quartz-albite-fluorite vein with 
selvage of muscovite-topaz- 
altered feldspar. 
Quartz-chalcopyrite-chlorite vein. 

Do. 
Quartz-chlorite-chalcopyrite greisen 
zone. 

Quartz-chlorite greisen. 
Chlorite greisen with pyritic center 
of vein. 
Zone of 12 chlorite veinlets and 
1.2-ft-wide quartz-albite-chlorite- 
biotite vein. 
Quartz-albite-chlorite-biotite vein 
from sample 132. 
Quartz-chlorite-biotite(?) veinlet zone. 
Zone of 50 quartz-chlorite-biotite(?) 
veinlets and 1.3-ft-wide quartz- 
chlorite greisen vein. 
Quartz-chlorite greisen vein from 
sample 135. 
Do. 



See explanatory notes at end of table. 



21 



Table C-1.— Results of quantitative geochemical analyses' of rock samples— Continued 



Sample' Type 



Length^ 
or area 



Analyses, ppm 



_Afl_ 



Au 



Sn 



U 



W 



CbjOs 



Field description'' 



138 

139 

140 

141 

142 
143 
144 



147 
148 
149 
151 
152 
153 
154 
155 
156 
157 
'158 
159 
160 
161 
162 
163 

164 
165 
166 

167 
168 

169 

170 

171 
172 
173 
174 
175 
176 
177 



178 
179 
180 
181 
182 
183 



.G NAp 

. C 21 ft 

.Ch 0.9 ft 



.Ch 

.C . 
.Ch 
.Ch 



.4 ft 



145 G NAp 

146 Ch 0.5 ft 



.Ch 0.3 ft 

.H NAp 

.H NAp 

.Ch 0.5 ft 

.Ch 0.3 ft 

.G NAp 

.Ch 0.3 ft 

.C 15 ft 

.C 0.2 ft 



.G . 
.G . 
.Ch 
.Ch 
.Ch 



.NAp 
.NAp 
.1 ft . 
.0.1 ft 
.0.4 ft 



.Ch 0.1 ft 

-Ch 1.8 ft 

.Ch 0.2 ft 

.Ch 7 ft . 

.C 0.2 ft 

. Ch 25 ft 

.C 0.3 ft 

.G NAp 

.C 0.3 ft 

.C 0.1 ft 

.G NAp 

.C 0.9 ft 

.C 0.9 ft 

.C 0.2 ft 

.C 0.6 ft 

.G NAp 



.Ch 1 ft . 

.C 0.1 ft 

.C 0.1 ft 

.C 0.2 ft 

.C 0.2 ft 

.C 0.3 ft 



1.5 


LD 


920 


66 


LD 


LD 


LD 


15 


LD 


0.164 


LD 


20 


LD 


LD 


75 


15 


LD 


LD 


7.6 


15 


LD 


LD 


140 


22 


LD 


.017 


230 


16 


1.6 


LD 


110 


16 


LD 


LD 


77 


17 


1.2 


.007 


100 


22 


1.1 


LD 


10.7 


18 


1 


.064 


8.9 


14 


2.6 


LD 


91 


24 


0.8 


LD 


340 


22 


LD 


0.015 


260 


15 


^6 


LD 


1,150 


23 


LD 


LD 


96 


19 


1.6 


LD 


9.9 


37 


1.2 


LD 


17.5 


22 


3.9 


'.007 


35 


22 


8.0 


LD 


70 


34 


6.9 


LD 


25 


28 


10.4 


^008 


67 


23 


19.2 


.009 


7,100 


24 


22.5 


LD 


230 


41 


2.5 


.033 


2,600 


22 


4.5 


LD 


46 


33 


4.6 


LD 


14.2 


24 


LD 


LD 


15.1 


24 


3.1 


LD 


LD 


22 




LD 


56 


19 


'.3 


LD 


49 


21 




LD 


21.7 


19 


2.0 


LD 


49 


16 


^6 


LD 


22.7 


19 


7.3 


LD 


940 


37 


1.6 


LD 


33 


27 


3.2 


LD 


460 


22 


1.4 


LD 


22.7 


22 


7.9 


'0.007 


140 


33 


9.5 


'.009 


500 


50 




LD 


77 


20 


3.5 


LD 


250 


25 


5.2 


LD 


200 


39 


21.2 


LD 


720 


50 



80 


LD 


20 


56 


400 


LD 


60 


LD 


14 


LD 


8 


LD 


280 


LD 


200 


LD 


32 


LD 


LD 


LD 


LD 


LD 


LD 


LD 


LD 


78 


12 


LD 


8 


LD 


6 


LD 


LD 


LD 


LD 


LD 


10 


LD 


50 


LD 


LD 


200 


LD 


LD 


LD 


LD 


240 


110 


ND 


LD 


12 


95 


LD 


77 


LD 


LD 


200 


87 


6 


LD 



80 
160 



78 
LD 



200 


LD 


160 


73 


16 


LD 


LD 


53 


LD 


53 


LD 


100 


60 


LD 


LD 


LD 


ND 


LD 


LD 




LD 


LD 


6 


LD 


10 


LD 



Muscovite-chlorite-fluorite-altered 
granite. 1 grain calcite observed. 
Zone of >75 quartz-chlorite veins 
and veinlets. 
Quartz-chlorite greisen with 2 quartz 
veinlets. 
Zone of approximately 25 quartz- 
chlorite veins and veinlets. 
Zone of quartz-chlorite-veinlets. 
Quartz-chlorite greisen fault zone. 
Quartz-chlorite-tourmaline-pyrite 
greisein vein. 
Composite of several diffuse quartz- 
chlorite greisen zones In area. 
Quartz-chlorite greisen with central 
quartz vein. 
Quartz-chlorite greisen. 
Quartz-chlorite veinlets. 

Do. 
Quartz-chlorite greisen. 
Quartz-chlorite veinlet zone. 
Quartz-chlorite veinlets. 
Quartz-chlorite greisen fault zone. 
Quartz-chlorite veinlet zone. 
Quartz-chlorite greisen fault zone. 
Do. 
Do. 
Do. 
Do. 
Do. 
Quartz-chlorite veinlets. 
Green fluorite vein with quartz- 
chlorite greisen selvages. 
Quartz-chlorite greisen fault zone. 
Quartz-chlorite greisen vein zone. 
Quartz-chlorite greisenized fault 
zone. 

Quartz-chlorite veinlet zone. 
Iron- and manganese-stained greisen 
vein. 

Quartz-chlorite veinlets with minor 
molybdenite. 
Quartz-chlorite greisenized fault 
zone. 
Do. 
Do. 
Coarse chlorite(?) greisen. 
Quartz-chlorite greisenized fault. 
Do. 
Do. 
Composite of quartz-chlorite greisen 
material from 25 ft of exposures 
along creek. 
Quartz-chlorite greisen 
Do. 
Do. 
Do. 
Do. 
Do. 



LD 
NA 
NAp 
ND 



Less than detection limit. 

Not analyzed. 

Not applicable. 

Not determined because of interterence 



Sample types: 
C Chip 
Ch Channel 
G Grab 
H High grade 

'Sn, Ta, and Cb (CbjOj) determined by XRF (Ta not detected); splits of samples with 50 ppm analyzed by AA; W by colorimetry; Th and U by radiometric 
techniques, and Ag and Au by fire assay-ICP. 
'Gaps in sample numbers correspond to samples listed in table 1 of main text or table A-1 of Appendix A. 
^True thicl<ness. 

'Supplemented with thin section observations. 

'Analysis is near detection limit and must be interpreted accordingly. 
'Also contains 28 ppm Mo, 3,900 ppm Cu, 1,700 ppm Pb, and 520 ppm Zn. 
'Also contains 1,500 ppm Cu, 230 ppm Pb, and 340 ppm Zn, but <2 ppm Mo. 
'Grab sample of material from several 0.4-ft-wide vems over 20-ft-wide interval. 
'Composite of 3 0.4-tt-wide veins over 10-ft-wide interval. 
'"Composite of 3 veins separated by 4 ft. 
"3 zones, 0.4, 0.7-, and 3.0-ft-wide, sampled over 25.0-ft interval. 



22 







Table C-2.— Results of semiquantitative emission spectrographic analyses' of rock samples 






Sam- 




pptn' pet 






ple 


As 


B Ba Be Cr Cu Ni Pb Sb Zn Zr Fe Li Mg 


Mn 


Ti 



I >200 100 200 20 

2 <100 100 200 20 

3 90 2,000 40 10 

4 <200 200 50 200 

5 <300 200 60 30 

6 <600 100 70 10 

7 <500 <60 <20 10 

8 <90 100 30 20 

9 <400 <100 <20 10 

II <500 90 <20 10 

12 <700 200 30 10 

13 <700 <70 30 10 

14 <90 100 100 10 

15 <90 <40 50 10 

16 <90 100 60 70 

17 <70 100 50 20 

18 <200 100 <20 20 

20 <90 <60 300 10 

21 <90 90 50 20 

22 <90 <40 <20 20 

23 <100 100 <20 30 

24 <200 100 40 40 

25 20,000 <60 <20 20 

26 <90 <80 40 10 

27 <300 500 90 30 

28 <100 90 70 400 

29 <200 100 40 50 

30 <200 100 70 50 

31 <90 <30 80 10 

33 <90 90 <20 20 

34 <300 <60 <20 20 

35 <400 <50 <20 20 

36 <600 600 <20 30 

37 <200 100 30 20 

38 <90 200 100 30 

39 <90 <80 60 20 

40 <400 <80 <20 20 

41 <90 100 70 20 

43 <300 clOO <20 40 

44 <100 <80 <20 20 

45 <90 80 40 10 

46 <500 <30 200 6 

47 <90 100 50 4 

48 <200 100 <20 8 

49 <90 <80 <20 700 

50 < 90 < 30 20 300 

51 <100 100 60 20 

52 < 200 200 < 20 20 

53 <500 <40 30 8 

55 <100 <40 <20 10 

56 400 <50 90 10 

57 < 200 400 200 80 

59 <90 90 50 20 

60 < 200 200 40 90 

61 <400 <60 100 40 

62 <90 100 <20 2C 

64 <200 800 60 100 

71 <90 <70 300 20 

72 <500 <40 2,000 6 

73 <700 90 100 40 

74 <100 600 90 30 

75 <400 <80 <20 60 

76 <300 <30 70 30 

77 <200 <40 <20 20 

78 <500 <70 <20 20 

79 <200 100 90 20 

80 <200 <60 60 20 

81 <300 900 20 10 

82 400 90 200 100 

83 <90 100 80 10 

84 400 90 100 60 

85 300 < 70 90 7 

86 400 80 20 30 

87 <600 <100 20 20 

88 <90 <90 50 40 

91 <200 <30 200 20 

92 300 <70 <20 20 

93 <200 <30 40 10 

94 500 100 400 50 

95 400 <80 700 60 

96 <90 90 90 20 

97 <90 90 50 100 

See explanatory notes at end of table. 



70 
40 
10 
30 
20 

30 
<8 

10 
<3 

20 

<5 
20 

<6 
10 

<5 

20 
<8 
40 
20 
<5 

20 
20 
30 
20 
30 



20 
<7 

20 
<3 

30 

10 
30 
50 
30 
<3 

<3 
<6 
30 
20 
20 

30 
40 
20 
70 
20 

20 
70 

30 
20 
20 
70 
10 

30 
<8 
20 
70 
30 

10 
30 
40 
40 
60 

70 
<7 
<4 
<3 

20 

30 
80 
90 
20 
20 



40 
<6 
<6 

400 



800 

10 

10 

200 

<6 

90 
20 
90 
90 
20 

10 
300 
<6 
100 
<6 



200 



30 2,000 

<7 40 

10 <6 

10 <6 

30 10 



9 
<6 
800 
<6 
<6 

10 
10 
<6 
<6 
10 

20 
<6 
10 
80 
<6 

700 
30 
30 
<6 

800 

20 
<6 

10 
<6 
<6 
100 
<6 



400 
20 
80 



80 
10 
50 
<6 
<6 

<6 
<7 
8 
<6 
40 

40 
<6 
<6 
40 



<4 

<3 

<10 

<9 



<20 
<20 
<20 
<40 
<2 

<50 
<2 
<60 
<30 
<40 

<30 

<10 

<30 

<6 

<3 



6 <8 

30 <5 

2,000 9 



20 



10 <6 <7 

20 30 <10 

20 300 <10 

<6 200 <6 

10 300 <5 



<7 
<30 

<10 
<40 

<2 

<10 

<2 

<90 

<10 

<30 
<6 
10 
<7 
<4 

<30 

<10 

10 

<5 

<7 

<20 
<9 
<8 
10 
<6 

<7 
9 

<30 

<40 

<30 

<6 

<3 

<4 
<6 
<3 
<9 
<6 

<2 
10 
<2 

<10 



10 

<100 

<90 

40 
<20 



2,000 
100 
<60 
800 
300 

400 
200 
200 
200 
<30 



<700 

<900 

<1,000 

< 1,000 

< 1,000 

<800 

< 1,000 

< 1,000 

< 1,000 
<800 



500 < 1,000 

500 <800 

60 < 1,000 

100 <900 

300 < 2,000 



300 

90 

600 

2,000 

<70 



< 1,000 

< 2,000 
<900 
<800 

< 2,000 



100 < 1,000 

500 < 1,000 

3.000 <600 

20 <600 

200 <600 

80 < 2,000 

300 < 1,000 

800 < 1,000 

400 < 1,000 

3,000 < 1,000 

4,000 < 2,000 

700 < 2,000 

<30 < 2,000 

100 < 1,000 

500 < 1,000 



200 
<40 

400 
<20 
<30 

200 
2,000 
<70 
<40 
<50 

<60 
300 
<30 
200 
<70 

<40 
400 
400 
<60 
<60 



<900 

< 1,000 

< 1,000 

< 2,000 

< 1,000 

< 1.000 
<600 
<600 
<600 

< 1,000 

< 1,000 

< 2,000 

< 2,000 
<600 

< 1,000 

< 2,000 
<600 
1,000 
<600 
<600 



< 20 < 1 ,000 
<40 <600 



1,000 
<30 
100 
<60 
<40 



< 1,000 

< 1,000 

< 1.000 

< 1,000 

< 8,000 



300 < 2,000 

200 < 2,000 

<70 <600 

200 <800 

<30 < 1,000 



20 
<7 
<5 
<2 



100 
500 
200 
<20 
<20 

<20 

5,000 

1,000 

<20 

<20 

<20 
90 
<60 
300 
<80 



<600 
<800 

< 1,000 
<900 
<600 

<600 

< 2,000 

< 1,000 

< 1,000 
<600 

< 1,000 

<80 
<600 

< 2,000 
<900 



1,000 
400 
700 
600 
600 

800 
1,000 

700 
2,000 

400 

800 
600 
500 
400 
1,000 

800 
500 
1,000 
800 
900 

600 
900 
700 
400 
700 



1,000 

1,000 

1,000 

600 

600 

1,000 
600 

1,000 
700 
400 

700 

2,000 

40 

30 

2,000 

2,000 
900 

1,000 
200 

2,000 

400 
700 
700 
400 
700 

500 
200 

700 
300 
800 
200 
700 

3,000 

2,000 

200 

200 

2,000 

800 
1,000 

500 
1,000 

100 

50 

2,000 

4,000 

800 

1,000 

3,000 
700 
300 
600 
900 



<30 
60 
<30 
<30 
<30 

30 

70 

<30 

<30 

<30 

40 
80 

100 
90 

<30 

<30 
40 

<30 
30 

300 

<30 
<30 
<30 
<30 
<30 



<30 
<30 
<30 
<30 
<30 

<30 
<30 
<30 
<30 
<30 

70 
,30 
<30 
<30 
<30 

<30 
<30 
<30 
100 
<30 

<30 
<30 
<30 
<30 
<30 

<30 
<30 

<30 
<30 
50 
<30 
<30 

<30 
<30 
<30 
60 
<30 

<30 
<30 
<30 
<30 
<30 

<30 
<30 
<30 
<30 
<30 

<30 
<30 
<30 
60 
<30 



700 <30 7 

700 <30 7 

900 <30 7 

800 40 8 

1,000 <30 6 



10 
7 
8 

10 
7 

9 
2 
3 
3 
10 



9 

7 
7 
7 
7 

6 
6 
10 



0.07 
.06 
.06 
.1 
.1 

.05 
.06 
.08 
.03 
.1 



.09 
.06 
.03 
.02 
.04 

.03 
.04 
.02 
.01 
.07 

.09 

.09 

.1 

.06 

.08 

>.08 
>.09 
>.04 

>.1 
>.2 

>.09 
>.04 
>.06 
>.06 
>.08 

>.08 
.002 
>.2 
>.2 
>.3 

>.06 
>.04 
>.09 
>.04 
>.04 

.03 
>.06 
>.05 
>.2 
>.09 

>.1 
>.3 

7.05 
< 0.003 

.03 
>.2 
.03 

.02 
>.09 
>.08 

.02 
>.04 

>.04 
.006 
.03 
.09 

<.005 

>.06 
.02 
.008 

>.05 
.02 

.03 
>.07 
<.002 
>.09 
>.04 



0.05 >4 

.2 >1 

.1 >2 

.03 >3 

.1 >2 



.1 

.03 

.1 

.09 

.08 



>2 
>4 
>2 
>5 



.6 



.1 >4 

.07 <2 

.1 >4 

.2 >2 

.2 >4 



.1 
.2 
.2 

.3 
.1 

.03 

.2 

.2 

.07 

.1 

.2 

.1 

.07 

.1 

.2 

.2 

.004 

.1 

.08 

.02 

.03 
ND 
.005 
.008 
.2 

.2 

.2 

.003 

.06 

.03 

.03 

.1 

.02 

.08 

.05 

.05 
.05 

0.09 
.9 
.1 

.06 
.06 

.1 

.2 

.02 

.04 

.1 

.1 

.08 

.1 

01 

.08 

.08 

.2 

.4 

.1 

.1 

.2 

.7 

.3 

.03 

.05 



>2 

>3 



>3 
>2 
>3 
>5 
>4 

>3 

>4 
>4 
>2 

>4 

>2 
>2 
>2 
>6 
>3 

>4 
>7 



>2 
3 
4 

>3 



>2 

6 
>3 



7 
4 

>5 

>5 
>3 

.f 
>2 

>4 
>2 
>2 
>2 
>2 



>2 

>3 

3 



<0.04 

.1 

<.04 

.05 

.03 

<.05 

<.03 

<.04 

<.3 

<.03 



.06 .08 >4 .05 

.04 .07 >2 <.08 

.07 .04 >7 .1 

.04 .04 >2 .05 

.09 .1 >3 .07 



.09 
.08 



>2 



>3 
>2 



<.07 
<.03 
<.06 
<.03 
<.03 

<.03 
<.04 
<.03 
<.03 
<.06 

<.03 
<.05 
.07 
<.07 
<.03 

<.03 
<.03 
<.03 
<.05 
<.09 

<.06 
<.03 
<.03 
<.03 
<.03 

<.03 
<.03 
<.03 
<.03 
<.03 

<.03 
<.04 
<.03 
<.05 
<.03 

<.03 
<.04 
<.03 
<.03 
<.03 

<.03 
<.03 

<0.05 

.3 

<.06 

<.04 

<.03 

<.03 
<.03 
<.04 
<.04 
<.03 

<.03 
<.03 
.09 
<.03 
<.03 

<.03 
<.03 
<.05 
<.03 
<.03 

<.03 
<.03 
<.05 
<.03 
<.03 



23 



Table C-2.— Results of semiquantitative emission spectrographic analyses' of rock samples— Continued 



Sam- 












ppm^ 
















pet 






pie 


As 


B 


Ba 


Be 


Cr 


Cu 


Ni 


Pb 


Sb 


Zn 


Zr 


Fe 


Li 


Mg 


Mn 


Ti 


100 ... 

101 ... 
103 ... 

105 .. . 

106 ... 


<400 

<200 

<200 

<90 

<90 


<60 
200 
100 

<80 
90 


50 
80 
70 
40 
30 


10 
30 
30 
100 
30 


<6 
60 
20 

10 
30 


<6 

9 

<6 

<6 

30 


<2 
<10 
<3 
<7 
<6 


300 
100 
2,000 
<60 
200 


< 1,000 
<900 
<700 
<600 

< 1,000 


500 
200 
900 
800 
500 


<30 
<30 
<30 
<30 
<30 


7 
7 
6 
5 
7 


>.06 
.03 
.02 

>.04 
.02 


.05 
.02 
.02 
.01 
.01 


>4 
>2 
>3 

.9 
>2 


<.03 
<.03 
<.03 
<.03 
<.03 


107 .. . 

108 ... 

109 ... 

110 ... 

111 ... 


<90 
<90 

400 
<100 

400 


90 
<80 
100 

90 
<80 


<20 

30 

100 

100 

30 


10 
30 
60 
200 
30 


30 
30 
70 
30 
6 


<6 
<6 
<6 
<6 
<6 


10 
<7 
<10 
<6 
<9 


<70 
100 
200 
100 
200 


<600 

< 1,000 

< 1,000 

< 1,000 

< 1,000 


800 
700 
500 
800 
2,000 


<30 
<30 
<30 
<30 
<30 


6 
6 
6 
7 
8 


>.07 
.03 
>.1 
>.1 
>.05 


.01 

.009 

.03 

.05 

.02 


>2 
>2 
>2 

>3 
>2 


<.03 
<.03 
<.03 
<.03 
<.03 


112 ... 

113 ... 

114 ... 

115 ... 

116 ... 


<100 

400 

300 

<200 

<200 


<80 
<30 
<70 
100 
<30 


40 
200 

60 
100 
100 


30 
> 1,000 
70 
50 
20 


50 
30 
20 
40 
<7 


<6 
70 
c6 
<6 

40 


<2 

<30 
<4 
<3 

<20 


1,000 

5,000 

400 

500 

2,000 


<900 
<900 
<900 
<900 
< 1,000 


2,000 
3,000 
2,000 
800 
2,000 


<30 
<30 
<30 
<30 
<30 


5 
7 
8 
7 
7 


.02 
.02 
>.2 

>.1 
.02 


.03 
.03 
.03 

.01 
.02 


>3 
>4 
>3 
>3 
>5 


<.03 
<.03 
<.03 
<.03 
<.03 


117 ... 

118 ... 

119 ... 

120 .. . 

121 ... 


200 
<100 

300 
<200 
<200 


<50 

90 

<50 

100 

<200 


30 
40 
<20 
50 
30 


10 

8 

< 2,000 

10 
> 3,000 


20 
80 
30 
60 
<3 


<6 
<6 
<6 

40 
200 


<5 

<8 

<8 

9 

<80 


<20 

<40 

<20 

60 

2,000 


<600 
<800 
1,000 
<600 
< 2,000 


600 

200 

400 

60 

5,000 


<30 
40 
<30 
<30 
<30 


6 

7 

8 

4 

10 


>.05 
>.3 
>.5 
>.2 

>.09 


.02 
.01 
.03 
.02 
<.005 


.5 
.4 
.4 
.2 
>10 


<.03 
<.03 
<.03 
<.03 
<.03 


122 ... 

123 ... 

124 ... 

125 .. . 

126 .. . 


<200 
<90 
600 
400 
<90 


100 
1,000 

100 
<80 
<80 


100 

20 

100 

200 

30 


30 
30 
20 
10 
10 


50 
60 
50 
50 
20 


200 
200 
<6 
40 
<6 


<9 
<7 
30 
40 
<3 


300 
<40 
<50 
1,000 
<80 


< 1,000 

<600 

800 

1,000 

<600 


700 
300 
200 
1,000 
700 


<30 
<30 
<30 
<30 
<30 


7 
3 
5 
6 
4 


>.1 
.01 

>.09 
.04 
.04 


.1 

.04 

.03 

.04 

02 


>?. 
2 

.3 
7 

.8 


<.03 
<.03 
<.03 
<.03 
<.03 


127 ... 

128 .. . 

129 .. . 

130 .. . 

131 ... 


<90 
<200 

<90 
<200 

<90 


<30 
<30 
<60 
100 
<30 


<20 
50 
20 
50 
40 


<1 

5 

20 

20 

5 


<3 

30 
10 
50 
10 


70,000 

80,000 

2,000 

70 

200 


50 

<8 

<20 

<20 

<20 


6,000 
9,000 
4,000 
500 
3,000 


<600 

< 1,000 

< 3,000 
<600 

< 1,000 


3,000 

2,000 

1,000 

700 

400 


<30 
<30 
<30 
<30 
<30 


8 
9 
8 
6 
9 


<.002 

.01 
>.08 
>.1 
>.05 


.007 

.04 

.05 

.05 

.2 


>2 
>3 
>6 
>3 
>5 


<.03 
>.04 
<.03 
<.03 
<.03 


132 ... 

133 .. . 

134 .. . 

135 .. . 

136 .. . 


<200 
400 
400 
300 
300 


200 
200 
200 
200 
200 


50 
60 
80 
60 
50 


30 

200 

100 

70 

50 


40 
90 
60 
50 
60 


10 
40 
40 
<6 
60 


10 
20 
10 
10 
20 


<40 
100 
<80 
<50 
100 


<600 
<600 
<600 
<600 
<600 


80 
40 
20 

70 
300 


<30 
<30 
<30 
<30 
<30 


3 
4 
4 
3 
6 


>.2 
>.3 

>.1 
>.1 
>.3 


.07 
.05 
.05 
.05 
.06 


.1 
.1 
.1 
.1 
.9 


<.03 
<.03 
<.04 
<.03 
<.03 


137 ... 

138 .. . 

139 .. . 

140 .. . 

141 ... 


<90 
6,000 

300 
<100 

<90 


200 
<100 
400 
500 
100 


<20 

40 

50 

<20 

<20 


6 
40 
20 
10 
20 


40 
20 
90 
90 
30 


20 
70 
<6 
<6 
<6 


10 
20 

9 
10 

8 


<20 
100 
<50 
<20 
<20 


<600 
<600 
<600 
<600 
<600 


100 

1,000 

90 

70 

70 


<30 
<30 
<30 
<30 
<30 


5 
6 
3 
5 
4 


>0.4 
>.3 
>.1 
>.2 
>.3 


0.05 
.03 
.02 
.02 
.007 


0.6 
.6 
.1 
.2 
.2 


<0.03 
<.03 
<.03 
<.03 
<.03 


142 .. . 

143 ... 

144 .. . 

145 .. . 

146 ... 


<200 
<200 
<200 
<90 
<100 


100 
300 
2,000 
500 
100 


<20 
<20 

<20 
<20 
100 


20 
100 

30 
400 

50 


40 
50 
20 
60 
50 


<6 
30 
<6 
40 
<6 


7 
20 

9 
40 
10 


<20 
<60 
<20 
<50 
<30 


<600 
<600 
<600 
< 1,000 
<600 


20 
200 
100 
200 
100 


<30 
<30 
<30 
<30 
<30 


3 
6 
4 
6 
5 


>.09 

>.1 

>.2 

>.1 

>.3 


.004 

.03 

.002 

.04 

.1 


.08 

.7 

.2 

.9 

.5 


<.03 
<.03 
<.03 
<.03 
<.05 


147 ... 

148 ... 

149 ... 

151 ... 

152 .. . 


400 
500 
600 
4,000 
700 


<70 
100 
100 
9,000 
100 


40 
40 
80 
50 
60 


100 

70 

20 

> 3,000 

30 


20 
60 
20 
<3 
30 


<6 
<6 
<6 
30 
40 


<4 
10 
40 
<2 
20 


<60 
80 
<70 
<20 
300 


<900 
<600 
2,000 
<600 
3,000 


9,000 

300 

40 

<1 

200 


<30 
<30 
<30 
<30 
<30 


8 
4 
3 

.002 
4 


>.06 
>.03 
.02 
<.002 
>.5 


.04 

.02 

.01 

.002 

.02 


>2 
2 
.2 
ND 
.4 


<.03 
<.03 
<.03 
<.03 
<.03 


153 .. . 

154 ... 

155 .. . 

156 ... 

157 .. . 


500 
<200 
400 
300 
300 


100 
100 
100 
90 
<80 


20 
<20 

70 
100 
<20 


20 
20 
20 
30 
9 


50 
10 
20 
<5 
20 


10 
20 

<6 
7 

<6 


20 
50 
20 
70 
30 


<40 
200 
<30 
90 
<20 


1,000 
7,000 
3,000 
6,000 
3,000 


50 
700 
200 
500 
500 


<30 
<30 
<30 
<30 
<30 


3 
5 
4 
5 
4 


>.5 
>.03 
>.3 
>.09 
.008 


.01 
.02 
.03 
.04 
.007 


.2 
<2 

.5 
>2 

.3 


<.03 
<.03 
<.03 
<.03 
<.03 


158 .. . 

159 .. . 

160 .. . 

161 ... 

162 .. . 


300 
400 
300 
300 
300 


100 
100 
100 
100 
90 


<20 
100 
30 
<20 
<20 


20 
600 

20 
200 

20 


10 
20 
30 
20 
20 


<6 
30 
40 
100 
<6 


40 
60 
40 
70 
40 


200 

800 

2,000 

1,000 

100 


5,000 
7,000 
3,000 
7,000 
5,000 


400 

900 

2,000 

3,000 

400 


<30 
<30 
<30 
<30 
<30 


5 
6 
5 
6 
5 


>.08 
>.94 
.03 
>.06 
>.2 


.007 
.02 
.03 
>.03 
.01 


.6 
>2 
>3 
>2 

.5 


<.03 
<.03 
<.03 
<.03 
<.03 


163 ... 

164 ... 

165 .. . 

166 ... 

167 ... 


<90 
300 
300 
300 
400 


<100 

90 

100 

<70 

90 


20 
30 
20 
80 
50 


100 
50 
30 
10 
10 


<8 
20 
20 
20 
30 


100 
<6 
20 
50 
<6 


30 
30 
20 
20 
20 


6,000 
90 
60 

1,000 
<20 


5,000 
2,000 
3,000 
1,000 
1,000 


4,000 

300 

800 

400 

70 


<30 
<30 
<30 
<30 
<30 


6 
5 
4 
4 
3 


>.05 
>.2 

.01 
.006 
>.1 


.02 

.009 

.02 

.009 

.003 


>7 
.6 
.4 
.9 
.08 


<.03 
<.03 
<.03 
<.03 
<.03 


168 ... 

169 .. . 

170 .. . 

171 ... 

172 .. . 


300 
400 
300 
400 
400 


<80 

100 

<80 

90 

80 


<20 

<20 

<20 

60 

60 


8 
40 
10 

8 
90 


20 
50 
20 
50 
30 


10 
<6 
<6 
<6 
<6 


20 
20 
20 
20 
50 


1,000 
<20 
<20 
<20 
<50 


300 

<600 

< 1,000 

1,000 

2,000 


300 
20 
100 
200 
200 


<30 
<30 
<30 
<30 
<30 


3 
4 
4 
4 
5 


<.002 

>.2 

>.3 

>.2 

>.1 


.002 

.003 

.005 

.02 

.05 


.3 

.09 

.1 

.1 

.2 


<.03 
<.03 
<.03 
<.03 
<.03 


173 .. . 

174 .. . 

175 .. . 

176 .. . 

177 .. . 


400 
<100 
400 
300 
400 


<60 
<30 
<70 
<70 
<50 


60 
80 
40 
50 
200 


<3 

10 
c 

1C 
200 


60 
<3 
40 
40 
20 


<6 
200 
<6 
<6 
<6 


40 
100 
60 
20 
20 


300 
300 
<40 
<20 
1,000 


<700 

< 3,000 

2,000 

900 

<600 


500 

1,000 

500 

200 

1,000 


<30 
<30 
<30 
<30 
<30 


4 
10 
6 
4 
3 


>.1 

>.3 

>.08 

>.2 

<.004 


.03 

.1 

.05 

.02 

.02 


.6 
>7 
.5 
.1 
.5 


<.03 
<.03 
<.03 
<.03 
<.03 


178 .. . 

179 .. . 

180 ... 

181 ... 

182 .. . 

183 ... 


400 
<100 
<200 
<200 

<90 
90 


<80 
100 
90 
100 
<70 
<60 


200 
30 
40 
<20 
<20 
100 


10 
10 
100 
20 
10 
8 


50 
40 
50 
30 
10 
10 


40 
30 
90 
100 
10 
70 


40 
20 
20 
10 
<2 
<20 


1,000 
200 
200 
<60 
500 
900 


1,000 
<600 
<600 
<600 
<700 
<800 


1,000 
800 
600 
100 

1,000 
800 


<30 
<30 
<30 
<30 
<30 
<30 


6 
5 
6 
4 
5 
8 


>.04 

>.09 

>.2 

>.2 

>.04 

>.09 


.04 
.02 
.06 
.07 
.02 
.07 


.7 
>2 
>3 

.2 
>2 
>3 


<.03 
<.03 
<.03 
<.03 
<.03 
<.04 



ND Not detected. 

'Au, Cd, Co, Ga, Mo, P, Pd, Pt, Sc, Ta, 

'Originally reported In percent 



V, and Y sought but not detected. 



NOTE.— No data available for samples 65 through 70, other gaps in sample numbers correspond to samples listed in table 1 of the main text 
or table A-1 of appendix A. 



24 



APPENDIX D.— RESULTS OF ANALYSES AND CALCULATED TIN GRADES OF PLACER 
SAMPLES COLLECTED ALONG NORTH FORK PREACHER CREEK 



Analysis, ppm 



Ta 



Sample Cb Ce Sn 

A 69 3,500 5,400 

B 68 3,100 5,100 

C 76 3,900 6,700 

D 110 6,200 14,000 

E 150 9,700 16,000 

F 110 7,000 11,600 

I 150 > 10,000 ^2.67 

J 120 6,200 20,000 

K 150 > 10,000 V.25 

L I > 10,000 ^6.54 

N I > 10,000 9,800 

O 16 445 750 

P I > 10,000 10,000 

Q 120 8,700 14,000 

R I 9,800 6,300 

S I > 10,000 2,900 

U 180 NA '1.75 

V I > 10,000 7,800 

W 135 9,600 M.87 

X 67 3,300 8,300 

Y I 8,100 2,100 

Z I 915 400 

DD NAp NAp M.80 NAp 



W 



Weight, Volume, Sn grade, 
g yd' Ib/yd^ 



Remarks 



7 


340 


310 


20.24 


0.375 


0.0006 


8 


430 


300 


18.63 


.247 


.0008 


LD 


520 


355 


20.45 


.175 


.0017 


12 


945 


530 


16.25 


.225 


.0022 


14 


1,395 


'750 


17.81 


.225 


.0028 


23 


900 


625 


19.81 


.384 


0013 


37 


1,350 


'1,000 


19.39 


1.00 


.0011 


33 


1,125 


510 


18.99 


^50 


.0017 


50 


> 2,000 


885 


19.39 


1.00 


.0031 



42 



> 2,000 



1,135 



20.49 



.388 



.0076 



24 


>1,170 


1,265 


16.97 


.150 


.0024 


LD 


25 


67 


19.03 


.150 


.0002 


26 


> 2,000 


1,150 


18.68 


.188 


.0022 


11 
11 
34 
LD 


1,550 

1,530 

540 

1,470 


'750 

1,270 

3,055 

NA 


18.65 
12.24 
25.8 
16.39 


.125 
.175 
.200 
.180 


.0046 
.0014 
.0004 
.0050 


20 


1,395 


2,310 


18.62 


.175 


.0016 


23 


> 2,000 


600 


20.59 


.213 


.0094 


9 


1,800 


225 


19.63 


.200 


.0019 


10 


1,125 


1,320 


18.27 


.150 


.0006 


9 


50 


'200 


29.7 


.050 


.0003 


Ap 


NAp 


NAp 


29.70 


.080 


.0400 



10-ft-high cutbank in older out- 
wash. 

Possibly slumped, older out- 
wash. 

5-ft-high cutbank, older out- 
wash(?), or possibly recent 
stream channel. 

5 ft of gravels beneath approx. 
15 ft of muck, older outwash. 

3 ft of gravels beneath approx. 
15 ft of muck, older outwash. 

3-ft-high cutbank In older out- 
wash. 

3-ft-high cutbank in recent 
gravels. Concentrated with 

jig- 

3-ft-cutbank in recent stream 
gravel bar. Concentrated with 

jig- 

3-ft-high cutbank in older(?) 
outwash. Sampling of tailings 
indicate this sample prob- 
ably only represents 62 pet 
recovery. Concentrated with 
jig- 

12-ft-high exposure of gravels, 
probably remnant of older 
outwash. 

Either older outwash or recent 
stream gravels. 

Gravel bar in recent active 
stream gravels. 

3-ft-high cutbank in more 
recent outwash. 
Do. 
Do. 

Cutbank in fan gravels. 

Recent gravels concentrated 
with 5-ft long sluice box. 

Lateral moraine(?), 10-ft-high- 
cutbank (older than recent 
outwash). 

5-ft-high cutbank in more recent 
outwash. Probably a poor 
sample. 

2-ft-high cutbank in more recent 
outwash. Probably a poor 
sample. 

Base of 1 5-ft-high cutbank in 
recent outwash gravels(?). 
Probably large dilution from 
colluvium. 

2-ft cutbank in alluvial fan(?) 
gravel. 

Small alluvial (outwash?) 
gravel bench. Sample concen- 
trated with 5-ft-long sluice 
box. 



I Not detected because of interference with Zr. 
'Interference noted because of Zr. 
'Percent. 
'Approximate only. 



LD Less than detection limit. NA Not analyzed. 



NAp Not applicable. 



U.S. GOVERNMENT PRINTING OFFICE: 1988 — 547-000/80,012 



INT.-BU.OF MINES,PGH.,PA. 28695 



/V «7 O C 



U.S. Department of the Interior 
Bureau of Mines— Prod, and Distr. 
Cochrans Mill Road 
P.O. Box 18070 
Pittsburgh. Pa. 15236 



OFFICIAL BUSINESS 
PENALTY FOR PRIVATE USE. S300 



I I Do not wish to receive this 
material, please remove 
from your mailing list. 

I I Address change. Please 
correct as indicated* 



AN EQUAL OPPORTUNITY EMPLOYER 



I* rO 



y"% 






* ^0 



r>^ 



V «o 



^^"^ 



t -s. 















^^^.^^* ••: 



••< 






y ♦2P^%X a^^'^V^^^^ ^4JI^\\. .^^""^^^ ^4^\\. S^^'m 



^0^ 
^^^ 





















C'®**^^^ y^vj^^V <'®,»^5j>^ y^*!!-^* \. <'''\-^,;fA >*!^^ 









n)r 
? >^^*. 






L!l% V >^*5«£^-^^ ^^••rjtA. >^*iafcS:-^^ 4.^ ••ri:.>«. >^*ii^*^^ 



•■ 
















• v> * 












.k*«* ^ 






I* '^^ 






6® •^ 









^..^ .• 







\./ .♦; 







'•• 








'• ^♦..^^ /j!^i/^. %..^ * 








i%»,^ 






^ » 



"-^c,<* 









0° /- 




.-1°^ 













^ A^ *:£ 



'bV" 



« 



* 4.^ «^ 




<J>-^ c " „ '^ 



--1°^ 











>•*. 

































♦'\ -.' 




















BOOKBINDING ||% * "^ t"* ♦ ,({\8rA o rS* A^ 



S^ . , . . °^- 

















■\., '..■,. 



